@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:ital,wght@0,300;0,400;0,500;0,600;0,700;0,800;1,300;1,400;1,500;1,600;1,700;1,800&family=Geist+Mono:wght@300;400;500;600;700;800&display=swap');

/* ===========================
   NextSem – style.css
   =========================== */

/* ── Reset & Variables ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  /* Common variables */
  --node-green: #68a063;
  --node-green-light: #8cc084;
  --node-green-glow: rgba(104, 160, 99, 0.35);
  --accent-cyan: #00d4aa;
  --accent-purple: #7c3aed;
  
  /* Dark mode (default) */
  --bg-dark: #0a0e13;
  --bg-card: #111827;
  --bg-card2: #0f1923;
  --bg-glass: rgba(255,255,255,0.04);
  --border: rgba(255,255,255,0.08);
  --border-hover: rgba(104,160,99,0.4);
  --text-primary: #f0f6f0;
  --text-secondary: #8b9eb5;
  --text-muted: #4a5568;
  --shadow-card: 0 4px 24px rgba(0,0,0,0.4);
  
  /* Font & Utilities */
  --font-sans: 'Plus Jakarta Sans', 'Inter', sans-serif;
  --font-heading: 'Plus Jakarta Sans', sans-serif;
  --font-mono: 'Geist Mono', 'JetBrains Mono', monospace;
  --radius-sm: 12px;
  --radius-md: 18px;
  --radius-lg: 24px;
  --radius-xl: 9999px; /* Gamified Pill */
  --shadow-glow: 0 0 40px rgba(104,160,99,0.15);
  --transition: all 0.2s cubic-bezier(0.4,0,0.2,1);
}

body.light-mode {
  --node-green: #52804d;
  --bg-dark: #f9f9fb;
  --bg-card: #ffffff;
  --bg-card2: #f1f1f5;
  --bg-glass: rgba(0,0,0,0.03);
  --border: rgba(0,0,0,0.08);
  --border-hover: rgba(82, 128, 77, 0.3);
  --text-primary: #111827;
  --text-secondary: #4b5563;
  --text-muted: #9ca3af;
  --shadow-card: 0 4px 20px rgba(0,0,0,0.06);
}

html { scroll-behavior: smooth; overflow-x: hidden !important; max-width: 100%; }

body {
  font-family: var(--font-sans);
  background: #05080c;
  color: var(--text-primary);
  overflow-x: hidden !important;
  max-width: 100%;
  line-height: 1.6;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  margin: 0;
  min-height: 100vh;
}

.app-container {
  width: 100%;
  max-width: 480px;
  min-height: 100vh;
  position: relative;
  background: var(--bg-dark);
  box-shadow: 0 0 60px rgba(0,0,0,0.8), 0 0 0 1px rgba(255,255,255,0.05);
  display: flex;
  flex-direction: column;
  padding-top: 68px; /* reserve space for fixed navbar */
  overflow-x: hidden;
}

/* ── Scrollbar ── */
/* Vertical scrollbar only - hide all horizontal scrollbars */
::-webkit-scrollbar { width: 5px; height: 0px; }  /* height:0 hides horizontal */
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--node-green); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: rgba(104,160,99,0.8); }
/* Hide scrollbar on horizontal-scroll containers */
.track-filter-strip::-webkit-scrollbar { display: none; }
.track-filter-strip { scrollbar-width: none; -ms-overflow-style: none; }

/* ── Navbar ── */
.navbar {
  position: fixed;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 480px;
  z-index: 1000;
  padding: 0 1.5rem;
  background: rgba(10,14,19,0.7);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  transition: var(--transition);
}
.navbar.scrolled {
  background: rgba(10,14,19,0.95);
  box-shadow: 0 4px 30px rgba(0,0,0,0.4);
}
.nav-container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
}
.logo-icon { 
  width: 36px;
  height: 24px;
  color: var(--node-green); 
  display: flex;
  align-items: center;
}
.logo-text-group {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  line-height: 1.15;
}
.logo-text {
  font-size: 1.25rem;
  font-weight: 700;
  text-transform: none;
  letter-spacing: -0.3px;
  color: #fff;
  white-space: nowrap;
}
.logo-subtext {
  font-size: 0.62rem;
  color: rgba(255, 255, 255, 0.8);
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: 1px;
}
.nav-links {
  display: flex;
  list-style: none;
  gap: 0.25rem;
  margin-left: auto;
}
.nav-link {
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.5rem 0.9rem;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}
.nav-link:hover { color: var(--text-primary); background: var(--bg-glass); }
.nav-actions { display: flex; align-items: center; gap: 1rem; }
.btn-start {
  background: var(--node-green);
  color: #fff;
  border: none;
  padding: 0.5rem 1.25rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.875rem;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
}
.btn-start:hover { background: var(--node-green-light); transform: translateY(-1px); }
.hamburger {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
  z-index: 1010;
}
.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: var(--transition);
}
.hamburger.active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.hamburger.active span:nth-child(2) {
  opacity: 0;
}
.hamburger.active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ── Hero Section ── */
.hero {
  min-height: calc(100vh - 68px);
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: 4rem;
  padding: 52px 2rem 80px;
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
}
.hero-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
}
.grid-overlay {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(104,160,99,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(104,160,99,0.04) 1px, transparent 1px);
  background-size: 60px 60px;
}
.orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(100px);
  animation: orbFloat 8s ease-in-out infinite;
}
.orb-1 { width: 500px; height: 500px; background: rgba(104,160,99,0.12); top: -100px; left: -100px; animation-delay: 0s; }
.orb-2 { width: 400px; height: 400px; background: rgba(0,212,170,0.07); top: 30%; right: -100px; animation-delay: -3s; }
.orb-3 { width: 350px; height: 350px; background: rgba(124,58,237,0.08); bottom: 10%; left: 30%; animation-delay: -5s; }

@keyframes orbFloat {
  0%,100% { transform: translateY(0) scale(1); }
  50% { transform: translateY(-30px) scale(1.05); }
}

.hero-content { display: flex; flex-direction: column; gap: 1.5rem; }

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: rgba(104,160,99,0.1);
  border: 1px solid rgba(104,160,99,0.3);
  color: var(--node-green-light);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.4rem 1rem;
  border-radius: 999px;
  width: fit-content;
  letter-spacing: 0.5px;
}
.badge-dot {
  width: 7px; height: 7px;
  background: var(--node-green);
  border-radius: 50%;
  animation: pulse 2s ease-in-out infinite;
}
@keyframes pulse {
  0%,100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.8); }
}

.hero-title {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -2px;
}
.gradient-text {
  background: linear-gradient(135deg, var(--node-green) 0%, var(--accent-cyan) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-subtitle {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 520px;
}
.hero-cta { display: flex; gap: 1rem; flex-wrap: wrap; }
.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: linear-gradient(135deg, var(--node-green) 0%, #4e9646 100%);
  color: #fff;
  border: none;
  padding: 0.85rem 1.75rem;
  border-radius: var(--radius-md);
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
  box-shadow: 0 4px 20px rgba(104,160,99,0.3);
}
.btn-primary svg { width: 18px; height: 18px; transition: transform 0.2s; }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 30px rgba(104,160,99,0.4); }
.btn-primary:hover svg { transform: translateX(4px); }
.btn-ghost {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--bg-glass);
  color: var(--text-primary);
  border: 1px solid var(--border);
  padding: 0.85rem 1.75rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
  backdrop-filter: blur(10px);
}
.btn-ghost:hover { border-color: var(--node-green); color: var(--node-green); transform: translateY(-2px); }

.hero-stats { display: flex; align-items: center; gap: 2rem; margin-top: 0.5rem; }
.stat { display: flex; flex-direction: column; }
.stat-num { font-size: 1.5rem; font-weight: 800; color: var(--node-green); line-height: 1; }
.stat-label { font-size: 0.75rem; color: var(--text-muted); font-weight: 500; margin-top: 2px; }
.stat-divider { width: 1px; height: 32px; background: var(--border); }

/* Code Window */
.hero-code-preview { display: flex; justify-content: center; align-items: center; }
.code-window {
  background: #0d1117;
  border: 1px solid rgba(104,160,99,0.2);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: 0 25px 80px rgba(0,0,0,0.6), 0 0 0 1px rgba(255,255,255,0.05);
  width: 100%;
  max-width: 520px;
  animation: floatCard 6s ease-in-out infinite;
  position: relative;
}
@keyframes floatCard {
  0%,100% { transform: translateY(0); }
  50% { transform: translateY(-12px); }
}
.code-window-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
  background: #161b22;
  border-bottom: 1px solid rgba(255,255,255,0.06);
}
.dot { width: 12px; height: 12px; border-radius: 50%; }
.dot.red { background: #ff5f57; }
.dot.yellow { background: #febc2e; }
.dot.green { background: #28c840; }
.code-filename {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
}
.code-window-body {
  padding: 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.7;
  color: #e6edf3;
  min-height: 220px;
  white-space: pre;
}
.code-cursor {
  position: absolute;
  bottom: 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--node-green);
  animation: blink 1s step-end infinite;
}
@keyframes blink { 0%,100%{opacity:1} 50%{opacity:0} }

/* ── Features Strip ── */
.features-strip {
  padding: 1.5rem 2rem;
  background: rgba(104,160,99,0.05);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  overflow: hidden;
}
.features-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}
.feature-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-weight: 500;
}
.feature-icon { font-size: 1rem; }

/* ── Section Shared ── */
.section-container { max-width: 1200px; margin: 0 auto; padding: 100px 2rem; }
.section-header { text-align: center; margin-bottom: 4rem; }
.section-tag {
  display: inline-block;
  background: rgba(104,160,99,0.1);
  border: 1px solid rgba(104,160,99,0.25);
  color: var(--node-green-light);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  padding: 0.35rem 1rem;
  border-radius: 999px;
  margin-bottom: 1rem;
}
.section-title {
  font-size: clamp(1.8rem, 3.5vw, 2.75rem);
  font-weight: 800;
  letter-spacing: -1px;
  line-height: 1.15;
  margin-bottom: 0.75rem;
}
.section-sub { color: var(--text-secondary); font-size: 1rem; max-width: 500px; margin: 0 auto; }

/* ── Curriculum Modules ── */
.modules-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}
.module-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}
.module-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--node-green), var(--accent-cyan));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s ease;
}
.module-card:hover { border-color: var(--border-hover); transform: translateY(-4px); box-shadow: var(--shadow-card), var(--shadow-glow); }
.module-card:hover::before { transform: scaleX(1); }
.module-header { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; }
.module-icon { font-size: 1.5rem; }
.module-num { font-size: 0.7rem; color: var(--text-muted); font-weight: 600; letter-spacing: 1px; text-transform: uppercase; }
.module-title { font-size: 1rem; font-weight: 700; margin-bottom: 0.5rem; }
.module-desc { font-size: 0.82rem; color: var(--text-secondary); line-height: 1.55; margin-bottom: 1rem; }
.module-tags { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.module-tag {
  background: rgba(104,160,99,0.1);
  color: var(--node-green-light);
  font-size: 0.68rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  font-family: var(--font-mono);
}
.module-level {
  position: absolute;
  top: 1rem;
  right: 1rem;
  font-size: 0.65rem;
  font-weight: 700;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
.level-beginner { background: rgba(40,200,100,0.12); color: #28c864; }
.level-intermediate { background: rgba(254,188,46,0.12); color: #febc2e; }
.level-advanced { background: rgba(255,95,87,0.12); color: #ff5f57; }

/* ── Lessons ── */
.lessons-section { background: linear-gradient(180deg, transparent, rgba(104,160,99,0.03), transparent); }

/* Horizontal scrollable tab strip */
.lesson-tabs-wrap {
  position: relative;
  margin-bottom: 2rem;
}
.lesson-tabs-wrap::after {
  content: '';
  position: absolute;
  right: 0; top: 0; bottom: 0;
  width: 48px;
  background: linear-gradient(to right, transparent, var(--bg));
  pointer-events: none;
  border-radius: 0 8px 8px 0;
}
.lesson-tabs {
  display: flex;
  flex-wrap: nowrap;
  overflow-x: auto;
  gap: 0;
  scrollbar-width: none;
  -ms-overflow-style: none;
  border-bottom: 2px solid var(--border);
  padding-bottom: 0;
  margin-bottom: 0;
}
.lesson-tabs::-webkit-scrollbar { display: none; }
.lesson-tab {
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  color: var(--text-secondary);
  padding: 0.7rem 1.25rem;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: color 0.2s, border-color 0.2s;
  white-space: nowrap;
  flex-shrink: 0;
}
.lesson-tab:hover { color: var(--text-primary); border-bottom-color: var(--border-hover); }
.lesson-tab.active {
  color: var(--node-green-light);
  border-bottom-color: var(--node-green);
}


.lesson-content {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  animation: fadeIn 0.3s ease;
}
@keyframes fadeIn { from{opacity:0;transform:translateY(10px)} to{opacity:1;transform:none} }
.lesson-inner { display: grid; grid-template-columns: 1fr 1fr; min-height: 420px; }
.lesson-theory { padding: 2.5rem; border-right: 1px solid var(--border); }
.lesson-theory h3 { font-size: 1.4rem; font-weight: 800; margin-bottom: 0.75rem; }
.lesson-theory p { color: var(--text-secondary); font-size: 0.9rem; line-height: 1.7; margin-bottom: 1rem; }
.lesson-theory ul { list-style: none; display: flex; flex-direction: column; gap: 0.5rem; }
.lesson-theory ul li {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
}
.lesson-theory ul li::before { content: '▸'; color: var(--node-green); flex-shrink: 0; margin-top: 2px; }
.lesson-code { display: flex; flex-direction: column; }
.lesson-code-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.25rem;
  background: #0d1117;
  border-bottom: 1px solid rgba(255,255,255,0.06);
}
.lesson-code-header span { font-family: var(--font-mono); font-size: 0.75rem; color: var(--text-muted); }
.btn-copy {
  background: rgba(104,160,99,0.15);
  border: 1px solid rgba(104,160,99,0.3);
  color: var(--node-green-light);
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.3rem 0.75rem;
  border-radius: 5px;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
}
.btn-copy:hover { background: rgba(104,160,99,0.3); }

/* Lesson Navigation Buttons */
.lesson-nav-buttons {
  display: none;
  justify-content: space-between;
  align-items: center;
  padding: 1.5rem 2.5rem;
  background: rgba(255, 255, 255, 0.01);
  border-top: 1px solid var(--border);
}
.btn-lesson-nav {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--bg-glass);
  border: 1px solid var(--border);
  color: var(--text-primary);
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  user-select: none;
}
.btn-lesson-nav:hover:not(:disabled) {
  border-color: var(--node-green);
  color: var(--node-green-light);
  background: rgba(104, 160, 99, 0.08);
}
.btn-lesson-nav:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}
.btn-lesson-nav.home-btn {
  background: rgba(104, 160, 99, 0.05);
  border-color: rgba(104, 160, 99, 0.2);
  color: var(--node-green-light);
}
.btn-lesson-nav.home-btn:hover {
  background: rgba(104, 160, 99, 0.15);
  border-color: var(--node-green);
}

.lesson-code pre {
  flex: 1;
  padding: 1.5rem;
  background: #0d1117;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.8;
  color: #e6edf3;
  overflow-x: hidden;
  white-space: pre-wrap;
  word-wrap: break-word;
  word-break: break-word;
}

/* Syntax highlighting classes */
.kw { color: #ff7b72; }
.fn { color: #d2a8ff; }
.str { color: #a5d6ff; }
.cmt { color: #8b949e; font-style: italic; }
.num { color: #79c0ff; }
.var { color: #ffa657; }
.obj { color: #7ee787; }

/* ── Playground ── */
.playground-section { background: rgba(104,160,99,0.02); }
.playground-wrapper {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.playground-sidebar {
  background: #0d1117;
  border-right: 1px solid var(--border);
  padding: 1.5rem 1rem;
}
.sidebar-tabs {
  display: flex;
  gap: 0.25rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
}
.sidebar-tab {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 700;
  cursor: pointer;
  padding: 0.4rem 0.60rem;
  border-radius: var(--radius-sm);
  transition: var(--transition);
  text-transform: uppercase;
  letter-spacing: 1px;
  font-family: var(--font-sans);
}
.sidebar-tab:hover {
  color: var(--text-primary);
  background: var(--bg-glass);
}
.sidebar-tab.active {
  color: var(--node-green-light);
  background: rgba(104,160,99,0.12);
}
.sidebar-content {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.sidebar-content.hidden {
  display: none;
}
.example-list, .challenge-list { list-style: none; display: flex; flex-direction: column; gap: 0.25rem; }
.example-item, .challenge-item {
  padding: 0.6rem 0.85rem;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
  font-weight: 500;
  border: 1px solid transparent;
}
.example-item:hover, .challenge-item:hover { background: var(--bg-glass); color: var(--text-primary); border-color: var(--border); }
.example-item.active, .challenge-item.active { background: rgba(104,160,99,0.12); color: var(--node-green-light); border-color: rgba(104,160,99,0.3); }

/* Challenge List Items with Badge */
.challenge-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.challenge-badge {
  font-size: 0.6rem;
  padding: 0.15rem 0.4rem;
  border-radius: 99px;
  font-weight: 700;
  text-transform: uppercase;
}
.challenge-badge.unsolved {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-muted);
}
.challenge-badge.solved {
  background: rgba(104, 160, 99, 0.15);
  color: var(--node-green-light);
}

/* Challenge card & feedback */
.challenge-instruction-card {
  margin-top: 1rem;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.challenge-title {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
}
.challenge-desc {
  font-size: 0.8rem;
  line-height: 1.5;
  color: var(--text-secondary);
  white-space: pre-line;
  margin: 0;
}
.challenge-status-badge {
  align-self: flex-start;
  font-size: 0.65rem;
  font-weight: 700;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  text-transform: uppercase;
}
.challenge-status-badge.unsolved {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-muted);
}
.challenge-status-badge.solved {
  background: rgba(104, 160, 99, 0.15);
  color: var(--node-green-light);
  border: 1px solid rgba(104, 160, 99, 0.3);
}

/* Verify Button styles */
.btn-verify {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  background: linear-gradient(135deg, #2b6cb0, #1a365d);
  color: #fff;
  border: none;
  padding: 0.45rem 1.1rem;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  font-weight: 700;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
  box-shadow: 0 2px 10px rgba(43, 108, 176, 0.3);
}
.btn-verify:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(43, 108, 176, 0.4);
}

.playground-editor { display: flex; flex-direction: column; }
.editor-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.25rem;
  background: #161b22;
  border-bottom: 1px solid var(--border);
}
.editor-tabs { display: flex; gap: 0.5rem; }
.editor-tab {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
  padding: 0.3rem 0.75rem;
  border-radius: 5px;
  border-bottom: 2px solid transparent;
}
.editor-tab.active { color: var(--node-green); border-bottom-color: var(--node-green); }
.editor-actions { display: flex; gap: 0.75rem; align-items: center; }
.btn-run {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  background: linear-gradient(135deg, var(--node-green), #4e9646);
  color: #fff;
  border: none;
  padding: 0.45rem 1.1rem;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  font-weight: 700;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
  box-shadow: 0 2px 10px rgba(104,160,99,0.3);
}
.btn-run svg { width: 14px; height: 14px; }
.btn-run:hover { transform: translateY(-1px); box-shadow: 0 4px 16px rgba(104,160,99,0.4); }
.btn-clear {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-secondary);
  padding: 0.45rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
}
.btn-clear:hover { border-color: #ff5f57; color: #ff5f57; }

.code-editor {
  background: #0d1117;
  color: #e6edf3;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.75;
  border: none;
  outline: none;
  resize: none;
  padding: 1.5rem;
  min-height: 260px;
  width: 100%;
  tab-size: 2;
}
.code-editor::placeholder { color: #4a5568; }

.output-panel { border-top: 1px solid var(--border); }
.output-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 1.25rem;
  background: #161b22;
  border-bottom: 1px solid var(--border);
}
.output-label { font-size: 0.72rem; font-weight: 700; color: var(--text-muted); text-transform: uppercase; letter-spacing: 1px; }
.btn-clear-output {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 0.72rem;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
}
.btn-clear-output:hover { color: var(--text-secondary); }
.output-content {
  background: #050a0e;
  padding: 1.25rem 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.7;
  color: #7ee787;
  min-height: 120px;
  white-space: pre-wrap;
  word-break: break-all;
}
.output-placeholder { color: #4a5568; font-style: italic; }
.output-error { color: #ff7b72; }
.output-log { color: #7ee787; }
.output-warn { color: #febc2e; }

/* ── Resources ── */
.resources-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}
.resource-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  text-decoration: none;
  color: var(--text-primary);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  transition: var(--transition);
}
.resource-card:hover { border-color: var(--border-hover); transform: translateY(-4px); box-shadow: var(--shadow-card), var(--shadow-glow); }
.resource-icon { font-size: 2rem; }
.resource-card h3 { font-size: 1rem; font-weight: 700; }
.resource-card p { font-size: 0.83rem; color: var(--text-secondary); line-height: 1.55; flex: 1; }
.resource-link { font-size: 0.8rem; color: var(--node-green); font-weight: 600; margin-top: 0.25rem; }

/* ── Footer ── */
.footer {
  border-top: 1px solid var(--border);
  padding: 3rem 2rem;
  text-align: center;
}
.footer-container { max-width: 1200px; margin: 0 auto; display: flex; flex-direction: column; align-items: center; gap: 0.75rem; }
.footer-brand { display: flex; align-items: center; gap: 0.5rem; font-size: 1.1rem; font-weight: 800; }
.footer-text { color: var(--text-secondary); font-size: 0.85rem; }
.footer-copy { color: var(--text-muted); font-size: 0.78rem; }
.footer-links { display: flex; gap: 1.5rem; flex-wrap: wrap; justify-content: center; margin-bottom: 0.25rem; }
.footer-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.82rem;
  font-weight: 500;
  transition: var(--transition);
}
.footer-link:hover { color: var(--node-green); }

/* ── Roadmap Section ── */
.roadmap-section { background: rgba(104,160,99,0.02); }
.roadmap-tracks { display: flex; flex-direction: column; gap: 1.5rem; }
.roadmap-track { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-md); overflow: hidden; transition: var(--transition); }
.roadmap-track:hover { border-color: var(--border-hover); box-shadow: var(--shadow-card); }
.roadmap-track-header { display: flex; align-items: center; gap: 1rem; padding: 1.25rem 1.5rem; border-bottom: 1px solid var(--border); }
.roadmap-track-header.frontend { background: linear-gradient(90deg, rgba(0,212,170,0.08), transparent); border-left: 3px solid var(--accent-cyan); }
.roadmap-track-header.backend  { background: linear-gradient(90deg, rgba(104,160,99,0.08), transparent); border-left: 3px solid var(--node-green); }
.roadmap-track-header.database { background: linear-gradient(90deg, rgba(124,58,237,0.08), transparent); border-left: 3px solid var(--accent-purple); }
.roadmap-track-icon { font-size: 1.75rem; }
.roadmap-track-header h3 { font-size: 1.05rem; font-weight: 700; margin-bottom: 0.15rem; }
.roadmap-track-header p  { font-size: 0.82rem; color: var(--text-secondary); }
.roadmap-steps { display: flex; align-items: center; flex-wrap: wrap; gap: 0.5rem; padding: 1.25rem 1.5rem; }
.roadmap-step { background: var(--bg-glass); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 0.45rem 1rem; font-size: 0.82rem; font-weight: 600; color: var(--text-secondary); white-space: nowrap; transition: var(--transition); }
.roadmap-step.highlight { background: rgba(104,160,99,0.12); border-color: rgba(104,160,99,0.4); color: var(--node-green-light); }
.roadmap-arrow { color: var(--text-muted); font-size: 1.1rem; font-weight: 700; }

/* ── Track Filter Buttons ── */
.track-filters { display: flex; flex-wrap: wrap; gap: 0.5rem; justify-content: center; margin-bottom: 2rem; }
.track-filter { background: var(--bg-glass); border: 1px solid var(--border); color: var(--text-secondary); padding: 0.5rem 1.25rem; border-radius: 999px; font-size: 0.85rem; font-weight: 600; cursor: pointer; font-family: var(--font-sans); transition: var(--transition); }
.track-filter:hover { border-color: var(--border-hover); color: var(--text-primary); }
.track-filter.active { background: rgba(104,160,99,0.15); border-color: var(--node-green); color: var(--node-green-light); }

/* Track-colored module card accents */
.module-card.track-frontend:hover { border-color: rgba(0,212,170,0.5); }
.module-card.track-backend:hover  { border-color: rgba(104,160,99,0.5); }
.module-card.track-devops:hover   { border-color: rgba(124,58,237,0.5); }
.module-card.track-frontend::before { background: linear-gradient(90deg, var(--accent-cyan), var(--node-green)); }
.module-card.track-backend::before  { background: linear-gradient(90deg, var(--node-green), var(--accent-cyan)); }
.module-card.track-devops::before   { background: linear-gradient(90deg, var(--accent-purple), #a855f7); }

/* ── Live Preview Playground (HTML/CSS/JS) ── */
.playground-mode-tabs { display: flex; gap: 0.5rem; margin-bottom: 1.5rem; justify-content: center; }
.playground-mode-tab { background: var(--bg-glass); border: 1px solid var(--border); color: var(--text-secondary); padding: 0.5rem 1.25rem; border-radius: var(--radius-sm); font-size: 0.85rem; font-weight: 600; cursor: pointer; font-family: var(--font-sans); transition: var(--transition); }
.playground-mode-tab.active { background: rgba(104,160,99,0.15); border-color: var(--node-green); color: var(--node-green-light); }
.live-preview-wrapper { display: none; grid-template-columns: 1fr 1fr; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-lg); overflow: hidden; min-height: 500px; }
.live-preview-wrapper.active { display: grid; }
.live-editor-panel { display: flex; flex-direction: column; background: #0d1117; border-right: 1px solid var(--border); }
.live-editor-tabs { display: flex; background: #161b22; border-bottom: 1px solid var(--border); }
.live-editor-tab { padding: 0.6rem 1rem; font-size: 0.78rem; font-family: var(--font-mono); font-weight: 600; color: var(--text-muted); cursor: pointer; border: none; border-bottom: 2px solid transparent; background: none; transition: var(--transition); }
.live-editor-tab.active { color: var(--node-green); border-bottom-color: var(--node-green); }
.live-editor-tab:hover  { color: var(--text-secondary); }
.live-code-area { display: none; flex: 1; background: #0d1117; color: #e6edf3; font-family: var(--font-mono); font-size: 0.8rem; line-height: 1.75; border: none; outline: none; resize: none; padding: 1.25rem; width: 100%; tab-size: 2; min-height: 420px; }
.live-code-area.active { display: block; }
.live-preview-panel { display: flex; flex-direction: column; background: #fff; }
.live-preview-header { display: flex; align-items: center; justify-content: space-between; padding: 0.6rem 1rem; background: #161b22; border-bottom: 1px solid var(--border); }
.live-preview-label { font-size: 0.72rem; font-weight: 700; color: var(--text-muted); text-transform: uppercase; letter-spacing: 1px; }
.btn-refresh-preview { background: rgba(104,160,99,0.15); border: 1px solid rgba(104,160,99,0.3); color: var(--node-green-light); font-size: 0.72rem; font-weight: 600; padding: 0.3rem 0.75rem; border-radius: 5px; cursor: pointer; font-family: var(--font-sans); transition: var(--transition); }
.btn-refresh-preview:hover { background: rgba(104,160,99,0.3); }
#live-preview-frame { flex: 1; border: none; width: 100%; min-height: 440px; background: #fff; }

/* Default styling for mobile-actions element in nav-links (hidden on desktop) */
.nav-links .mobile-actions,
.nav-links .mobile-only {
  display: none;
}

/* ══════════════════════════════════════════
   Responsive – Tablet (≤900px)
   ══════════════════════════════════════════ */
@media (max-width: 900px) {
  /* ── Hero ── */
  .hero {
    grid-template-columns: 1fr;
    padding-top: 32px;
    padding-bottom: 60px;
    text-align: center;
    gap: 2.5rem;
  }
  .hero-content { align-items: center; }
  .hero-subtitle { text-align: center; max-width: 100%; }
  .hero-cta { justify-content: center; }
  .hero-stats { justify-content: center; }
  .hero-code-preview { display: none; }

  /* ── Lessons ── */
  .lesson-inner { grid-template-columns: 1fr; }
  .lesson-theory { border-right: none; border-bottom: 1px solid var(--border); }

  /* ── Playground ── */
  .playground-wrapper { grid-template-columns: 1fr; }
  .playground-sidebar { border-right: none; border-bottom: 1px solid var(--border); }

  /* ── Section padding ── */
  .section-container { padding: 70px 1.5rem; }

  /* ── Navbar: hamburger appears, links collapse ── */
  .nav-container {
    justify-content: flex-start;
    gap: 0.75rem;
    position: relative;
  }
  .hamburger { display: flex; }
  .nav-actions { margin-left: auto; gap: 0.75rem; }
  .nav-links {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: rgba(10, 14, 19, 0.98);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    padding: 0 1.5rem;
    gap: 0;
    z-index: 999;
    align-items: stretch;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height 0.3s ease, opacity 0.3s ease, padding 0.3s ease;
  }
  .nav-links.active {
    max-height: 600px;
    opacity: 1;
    padding: 1.25rem 1.5rem;
    gap: 0.4rem;
  }
  .nav-link {
    display: block;
    padding: 0.75rem 1rem;
    width: 100%;
    border-radius: var(--radius-sm);
  }
}

/* ══════════════════════════════════════════
   Responsive – Mobile (≤600px)
   ══════════════════════════════════════════ */
@media (max-width: 600px) {
  /* ── Base ── */
  body { overflow-x: hidden; }

  /* ── Navbar ── */
  .nav-container .btn-start { display: none !important; }
  .nav-container .btn-auth { padding: 0.4rem 0.75rem; font-size: 0.78rem; }
  .nav-actions { gap: 0.4rem; }

  /* Show user panel (avatar only) */
  .nav-container .user-panel {
    display: flex;
    gap: 0;
    align-items: center;
  }
  .nav-container .user-panel .user-name { display: none !important; }
  .nav-container .user-panel .btn-signout { display: none !important; }
  .nav-container .user-panel .user-avatar {
    cursor: pointer;
    outline: 2px solid transparent;
    transition: outline-color 0.2s;
  }
  .nav-container .user-panel .user-avatar:hover { outline-color: var(--node-green); }
  .nav-links .mobile-only {
    display: block;
  }

  /* Dropdown mobile actions */
  .nav-links .mobile-actions {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    padding-top: 1rem;
    margin-top: 0.5rem;
    border-top: 1px solid var(--border);
  }
  .nav-links .mobile-actions .btn-start {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    width: 100%;
    padding: 0.75rem;
    font-size: 0.9rem;
  }
  .nav-links .mobile-actions .btn-auth {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    width: 100%;
    padding: 0.75rem;
    font-size: 0.9rem;
  }
  .nav-links .mobile-actions .user-panel {
    display: flex;
    width: 100%;
    justify-content: space-between;
    align-items: center;
    padding: 0.5rem 0.75rem;
    background: rgba(255,255,255,0.03);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
  }

  /* ── Hero ── */
  .hero {
    padding: 24px 1rem 50px;
    gap: 2rem;
    min-height: auto;
  }
  .hero-title { font-size: clamp(1.9rem, 7vw, 2.4rem); letter-spacing: -1px; }
  .hero-subtitle { font-size: 0.92rem; }
  .hero-badge { font-size: 0.72rem; }
  .hero-cta { flex-direction: column; align-items: center; gap: 0.75rem; }
  .btn-primary, .btn-ghost { width: 100%; justify-content: center; padding: 0.8rem 1.25rem; }
  .hero-stats { gap: 1.25rem; }
  .stat-num { font-size: 1.25rem; }

  /* ── Features strip ── */
  .features-strip { padding: 1rem; }
  .features-container {
    justify-content: center;
    gap: 0.75rem;
  }
  .feature-item { font-size: 0.78rem; }

  /* ── Section shared ── */
  .section-container { padding: 50px 1rem; }
  .section-header { margin-bottom: 2.5rem; }
  .section-title { font-size: clamp(1.5rem, 5vw, 2rem); letter-spacing: -0.5px; }
  .section-sub { font-size: 0.88rem; }

  /* ── Curriculum modules ── */
  .modules-grid { grid-template-columns: 1fr; gap: 0.85rem; }
  .module-card { padding: 1.25rem; }
  .module-title { font-size: 0.95rem; }
  .module-desc { font-size: 0.8rem; }

  /* ── Lessons ── */
  .lesson-tabs-wrap { display: none; }
  .lesson-theory { padding: 1.5rem 1rem; }
  .lesson-theory h3 { font-size: 1.15rem; }
  .lesson-theory p { font-size: 0.85rem; }
  .lesson-code pre { font-size: 0.75rem; padding: 1rem; }
  .lesson-nav-buttons { display: flex; padding: 1.25rem 1rem; }
  .btn-lesson-nav { padding: 0.5rem 0.9rem; font-size: 0.8rem; }

  /* ── Playground ── */
  .playground-wrapper { border-radius: var(--radius-md); }
  .playground-sidebar { padding: 1rem 0.75rem; }
  .code-editor { min-height: 200px; font-size: 0.78rem; padding: 1rem; }
  .output-content { min-height: 90px; font-size: 0.75rem; padding: 1rem; }
  .editor-actions { gap: 0.4rem; }
  .btn-run, .btn-clear, .btn-verify { padding: 0.4rem 0.75rem; font-size: 0.76rem; }

  /* ── Quiz ── */
  .quiz-card, .quiz-wrapper { border-radius: var(--radius-md); }
  .quiz-question-text { font-size: 0.92rem; }
  .quiz-options { gap: 0.5rem; }
  .quiz-option { padding: 0.65rem 0.9rem; font-size: 0.85rem; }

  /* ── Resources ── */
  .resources-grid { grid-template-columns: 1fr; gap: 0.85rem; }
  .resource-card { padding: 1.25rem; }

  /* ── Progress section ── */
  .progress-header { flex-direction: column; align-items: flex-start; gap: 0.25rem; }
  .progress-label { font-size: 0.85rem; }

  /* ── Auth modal ── */
  .auth-modal-card { padding: 1.5rem 1.25rem; margin: 0 1rem; }

  /* ── Footer ── */
  .footer { padding: 2rem 1rem; }
  .footer-links { gap: 1rem; }
  .footer-text, .footer-copy { font-size: 0.78rem; }

  /* ── Ads ── */
  .ad-slot { padding: 0.5rem; }
}

/* ═══════════════════════════════════════
   Firebase Auth UI
   ═══════════════════════════════════════ */

/* ── Nav: Auth button ── */
.btn-auth {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  background: rgba(104,160,99,0.1);
  border: 1px solid rgba(104,160,99,0.35);
  color: var(--node-green-light);
  padding: 0.45rem 1.1rem;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
}
.btn-auth:hover { background: rgba(104,160,99,0.2); border-color: var(--node-green); }

/* ── Nav: User Panel ── */
.user-panel {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.user-avatar {
  width: 34px; height: 34px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--node-green), var(--accent-cyan));
  display: flex; align-items: center; justify-content: center;
  font-weight: 800;
  font-size: 0.85rem;
  color: #fff;
  flex-shrink: 0;
  overflow: hidden;
}
.user-name {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
  max-width: 110px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.btn-signout {
  background: none;
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 50%;
  width: 28px; height: 28px;
  display: flex; align-items: center; justify-content: center;
  cursor: pointer;
  color: var(--text-muted);
  transition: var(--transition);
  flex-shrink: 0;
}
.btn-signout:hover { border-color: #ff5f57; color: #ff5f57; }

/* ── Progress Bar ── */
.progress-section {
  background: rgba(104,160,99,0.05);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.progress-section .section-container { padding: 1.25rem 2rem; }
.progress-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.75rem;
}
.progress-label {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--node-green-light);
  text-transform: uppercase;
  letter-spacing: 1px;
}
.progress-text {
  font-size: 0.8rem;
  color: var(--text-secondary);
}
.progress-track {
  width: 100%;
  height: 8px;
  background: rgba(255,255,255,0.06);
  border-radius: 999px;
  overflow: hidden;
}
.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--node-green), var(--accent-cyan));
  border-radius: 999px;
  transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 0 12px rgba(104,160,99,0.5);
}

/* ── Module: Completed badge ── */
.module-card.completed {
  border-color: rgba(104,160,99,0.5);
  background: rgba(104,160,99,0.06);
}
.done-badge {
  position: absolute;
  bottom: 1rem;
  right: 1rem;
  width: 24px; height: 24px;
  background: var(--node-green);
  color: #fff;
  border-radius: 50%;
  font-size: 0.7rem;
  font-weight: 900;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 0 10px rgba(104,160,99,0.5);
}

/* ── Auth Modal Backdrop ── */
.auth-modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(5,8,12,0.85);
  backdrop-filter: blur(12px);
  z-index: 9000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  animation: backdropIn 0.2s ease;
}
.auth-modal-backdrop.open { display: flex; }
@keyframes backdropIn { from{opacity:0} to{opacity:1} }

/* ── Auth Modal Card ── */
.auth-modal-card {
  background: #0f1923;
  border: 1px solid rgba(104,160,99,0.25);
  border-radius: var(--radius-xl);
  padding: 2.5rem 2rem;
  width: 100%;
  max-width: 420px;
  position: relative;
  box-shadow: 0 30px 80px rgba(0,0,0,0.7), 0 0 0 1px rgba(255,255,255,0.05);
  animation: modalIn 0.25s cubic-bezier(0.34,1.56,0.64,1);
}
@keyframes modalIn { from{opacity:0;transform:scale(0.9) translateY(20px)} to{opacity:1;transform:none} }

.auth-modal-close {
  position: absolute;
  top: 1.25rem; right: 1.25rem;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.08);
  color: var(--text-muted);
  width: 32px; height: 32px;
  border-radius: 50%;
  font-size: 0.85rem;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: var(--transition);
  line-height: 1;
}
.auth-modal-close:hover { background: rgba(255,95,87,0.15); border-color: #ff5f57; color: #ff5f57; }

/* ── Auth Logo ── */
.auth-logo {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-size: 1.4rem;
  font-weight: 800;
  margin-bottom: 0.4rem;
}
.auth-tagline {
  text-align: center;
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
}

/* ── Google Sign-In ── */
.google-sign-in-btn {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  background: rgba(255,255,255,0.05);
  border: 1px solid rgba(255,255,255,0.12);
  color: var(--text-primary);
  padding: 0.7rem 1.5rem;
  border-radius: var(--radius-md);
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
  margin-bottom: 1.25rem;
}
.google-sign-in-btn:hover { background: rgba(255,255,255,0.1); border-color: rgba(255,255,255,0.2); }

/* ── Divider ── */
.auth-divider {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.25rem;
  color: var(--text-muted);
  font-size: 0.75rem;
}
.auth-divider::before, .auth-divider::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

/* ── Auth Tabs ── */
.auth-tabs {
  display: flex;
  background: rgba(255,255,255,0.04);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 3px;
  margin-bottom: 1.25rem;
}
.auth-tab {
  flex: 1;
  background: none;
  border: none;
  color: var(--text-muted);
  padding: 0.45rem;
  border-radius: 7px;
  font-size: 0.83rem;
  font-weight: 600;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
}
.auth-tab.active {
  background: rgba(104,160,99,0.18);
  color: var(--node-green-light);
  box-shadow: 0 1px 4px rgba(0,0,0,0.3);
}

/* ── Auth Messages ── */
.auth-error {
  background: rgba(255,95,87,0.1);
  border: 1px solid rgba(255,95,87,0.3);
  color: #ff7b72;
  padding: 0.65rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  margin-bottom: 1rem;
}
.auth-success {
  background: rgba(104,160,99,0.1);
  border: 1px solid rgba(104,160,99,0.3);
  color: var(--node-green-light);
  padding: 0.65rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  margin-bottom: 1rem;
}

/* ── Auth Form ── */
.auth-form {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.auth-field {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}
.auth-field label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-secondary);
  letter-spacing: 0.3px;
}
.auth-field input {
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.88rem;
  padding: 0.65rem 0.9rem;
  outline: none;
  transition: border-color 0.2s;
  width: 100%;
}
.auth-field input::placeholder { color: var(--text-muted); }
.auth-field input:focus { border-color: var(--node-green); box-shadow: 0 0 0 3px rgba(104,160,99,0.15); }

.auth-submit-btn {
  background: linear-gradient(135deg, var(--node-green), #4e9646);
  color: #fff;
  border: none;
  padding: 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 700;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: var(--transition);
  box-shadow: 0 4px 16px rgba(104,160,99,0.3);
  margin-top: 0.25rem;
}
.auth-submit-btn:hover { transform: translateY(-1px); box-shadow: 0 6px 24px rgba(104,160,99,0.4); }

/* ── Toast Notification ── */
#firebase-toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(80px);
  background: #111827;
  border: 1px solid rgba(104,160,99,0.4);
  color: var(--node-green-light);
  padding: 0.75rem 1.5rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
  box-shadow: 0 10px 40px rgba(0,0,0,0.5);
  z-index: 9999;
  opacity: 0;
  transition: opacity 0.3s ease, transform 0.4s cubic-bezier(0.34,1.56,0.64,1);
  pointer-events: none;
}
#firebase-toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ═══════════════════════════════════════
   Google AdSense Ad Slots
   ═══════════════════════════════════════ */

/* ── Base ad slot wrapper ── */
.ad-slot {
  position: relative;
  width: 100%;
  text-align: center;
  padding: 1rem 2rem;
  background: rgba(255,255,255,0.015);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  overflow: hidden;
}

/* Shimmer effect while ad loads */
.ad-slot::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    90deg,
    transparent 0%,
    rgba(255,255,255,0.02) 50%,
    transparent 100%
  );
  background-size: 200% 100%;
  animation: adShimmer 2s ease-in-out infinite;
  pointer-events: none;
}
@keyframes adShimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}

/* ── "Advertisement" label ── */
.ad-label {
  display: block;
  font-size: 0.6rem;
  font-weight: 600;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 0.4rem;
}

/* ── Leaderboard (728×90) after features strip ── */
.ad-slot-leaderboard {
  padding: 0.75rem 2rem;
}
.ad-slot-leaderboard ins {
  max-width: 728px;
  margin: 0 auto;
  min-height: 90px;
}

/* ── In-content rectangle between lessons & playground ── */
.ad-slot-rectangle {
  padding: 2.5rem 2rem;
  background: transparent;
  border-top: none;
  border-bottom: none;
}
.ad-slot-rectangle ins {
  max-width: 728px;
  margin: 0 auto;
  min-height: 250px;
  border-radius: var(--radius-md);
  overflow: hidden;
}

/* ── Footer banner ── */
.ad-slot-footer {
  padding: 1.5rem 2rem;
  background: rgba(104,160,99,0.02);
}
.ad-slot-footer ins {
  max-width: 970px;
  margin: 0 auto;
  min-height: 90px;
}

/* ── Responsive: hide leaderboard on mobile ── */
@media (max-width: 768px) {
  .ad-slot-leaderboard { display: none; }
  .ad-slot-rectangle ins { min-height: 200px; }
}

/* ===========================
   NextSem – Quiz Section Styles
   =========================== */
.quiz-section {
  padding: 80px 2rem 100px;
  background: radial-gradient(ellipse at bottom, rgba(124,58,237,0.04) 0%, transparent 70%);
  border-bottom: 1px solid var(--border);
}
.quiz-wrapper {
  max-width: 780px;
  margin: 0 auto;
}
.quiz-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  box-shadow: var(--shadow-card);
  position: relative;
  overflow: hidden;
}
.quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}
.quiz-progress-text {
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-weight: 500;
}
.quiz-score-badge {
  background: rgba(104,160,99,0.1);
  border: 1px solid rgba(104,160,99,0.25);
  color: var(--node-green-light);
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  font-size: 0.78rem;
  font-weight: 600;
}
.quiz-progress-bar {
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  margin-bottom: 2rem;
  position: relative;
  overflow: hidden;
}
.quiz-progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--node-green), var(--accent-cyan));
  width: 0%;
  transition: width 0.3s ease;
}
.quiz-question-text {
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1.5;
  margin-bottom: 1.75rem;
  color: var(--text-primary);
}
.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
  margin-bottom: 2rem;
}
.quiz-option {
  width: 100%;
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 1.1rem 1.4rem;
  text-align: left;
  color: var(--text-secondary);
  font-size: 0.95rem;
  font-family: var(--font-sans);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.quiz-option:hover:not(.disabled) {
  border-color: var(--border-hover);
  background: rgba(255,255,255,0.06);
  color: var(--text-primary);
  transform: translateX(4px);
}
.quiz-option.selected {
  border-color: var(--accent-purple);
  background: rgba(124,58,237,0.08);
  color: var(--text-primary);
}
.quiz-option.correct {
  border-color: var(--node-green) !important;
  background: rgba(104,160,99,0.12) !important;
  color: var(--text-primary) !important;
}
.quiz-option.incorrect {
  border-color: #ef4444 !important;
  background: rgba(239,68,68,0.12) !important;
  color: var(--text-primary) !important;
}
.quiz-option-marker {
  font-weight: 700;
  font-size: 0.9rem;
}
.quiz-feedback {
  background: rgba(104,160,99,0.05);
  border-left: 4px solid var(--node-green);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 1.25rem;
  margin-bottom: 2rem;
  display: none;
}
.quiz-feedback.incorrect-feedback {
  background: rgba(239,68,68,0.05);
  border-left-color: #ef4444;
}
.quiz-feedback-title {
  font-weight: 700;
  font-size: 0.9rem;
  margin-bottom: 0.3rem;
  display: block;
}
.quiz-feedback.correct-feedback .quiz-feedback-title { color: var(--node-green-light); }
.quiz-feedback.incorrect-feedback .quiz-feedback-title { color: #f87171; }
.quiz-feedback p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0;
}
.quiz-actions {
  display: flex;
  justify-content: flex-end;
}
.btn-quiz-next {
  background: linear-gradient(135deg, var(--node-green), #4e9646);
  color: #fff;
  border: none;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 4px 16px rgba(104,160,99,0.25);
  transition: var(--transition);
}
.btn-quiz-next:hover:not(:disabled) {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(104,160,99,0.35);
}
.btn-quiz-next:disabled {
  background: var(--border);
  color: var(--text-muted);
  cursor: not-allowed;
  box-shadow: none;
}

/* Results Card */
.quiz-results-card {
  text-align: center;
  padding: 3rem 2rem;
}
.quiz-results-icon {
  font-size: 4rem;
  margin-bottom: 1.5rem;
  display: block;
}
.quiz-results-score {
  font-size: 3rem;
  font-weight: 900;
  color: var(--node-green-light);
  line-height: 1;
  margin-bottom: 0.5rem;
}
.quiz-results-score span {
  color: var(--text-muted);
  font-size: 1.5rem;
  font-weight: 500;
}
.quiz-results-heading {
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: 1rem;
}
.quiz-results-text {
  color: var(--text-secondary);
  font-size: 0.98rem;
  max-width: 480px;
  margin: 0 auto 2.5rem;
  line-height: 1.6;
}
.btn-quiz-restart {
  background: transparent;
  border: 1px solid var(--border-hover);
  color: var(--node-green-light);
  padding: 0.75rem 2rem;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
}
.btn-quiz-restart:hover {
  background: rgba(104,160,99,0.08);
  color: var(--text-primary);
}

@media (max-width: 580px) {
  .quiz-card { padding: 1.5rem; }
  .quiz-header { flex-direction: column; gap: 0.75rem; align-items: flex-start; }
}

/* ==========================================
   Mobile Optimization Overrides (max-width: 768px)
   ========================================== */
@media (max-width: 768px) {
  html, body {
    overflow-x: hidden;
    width: 100%;
  }

  /* Prevent elements from pushing out body width */
  pre, code, textarea, input, select, .playground-wrapper, .quiz-card {
    max-width: 100% !important;
  }

  /* Global sections */
  .section-container {
    padding: 60px 1.25rem;
  }
  .section-header {
    margin-bottom: 2.5rem;
  }

  /* Hero Section */
  .hero {
    min-height: auto;
    padding: 32px 1.25rem 40px;
    gap: 2.5rem;
  }
  .hero-title {
    font-size: clamp(2.2rem, 6vw, 3rem);
    letter-spacing: -1px;
  }
  .hero-subtitle {
    font-size: 0.95rem;
    line-height: 1.6;
  }
  .hero-cta {
    width: 100%;
    flex-direction: column;
    gap: 0.75rem;
  }
  .btn-primary, .btn-ghost {
    width: 100%;
    justify-content: center;
  }
  .hero-stats {
    width: 100%;
    justify-content: space-around;
    gap: 1rem;
    flex-wrap: wrap;
  }
  .hero-stats .stat {
    flex: 1 1 30%;
    align-items: center;
    text-align: center;
  }
  .hero-stats .stat-divider {
    display: none;
  }

  /* Features Strip */
  .features-strip {
    padding: 1.25rem 1rem;
  }
  .features-container {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }
  
  /* Lesson tabs & theory */
  .lesson-tabs {
    flex-wrap: nowrap;
    justify-content: flex-start;
    overflow-x: auto;
    padding: 0.25rem 0.5rem;
    margin-left: -1rem;
    margin-right: -1rem;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
    gap: 0.4rem;
  }
  .lesson-tabs::-webkit-scrollbar {
    display: none;
  }
  .lesson-tab {
    flex: 0 0 auto;
    padding: 0.45rem 1rem;
    font-size: 0.8rem;
  }
  .lesson-theory {
    padding: 1.5rem;
  }
  .lesson-code-header {
    padding: 0.75rem 1rem;
  }

  /* Playground Section */
  .playground-wrapper {
    grid-template-columns: 1fr;
  }
  .playground-sidebar {
    padding: 1.25rem 1rem;
  }
  .editor-header {
    flex-direction: column;
    align-items: stretch;
    gap: 0.75rem;
    padding: 1rem;
  }
  .editor-actions {
    justify-content: flex-end;
    width: 100%;
    flex-wrap: wrap;
    gap: 0.5rem;
  }
  .btn-run, .btn-verify, .btn-clear {
    flex: 1 1 auto;
    justify-content: center;
    padding: 0.5rem 0.75rem;
    font-size: 0.78rem;
  }
  .code-editor {
    min-height: 200px;
    padding: 1rem;
  }
  .output-content {
    min-height: 100px;
    padding: 1rem;
  }

  /* Enable word-wrapping in code blocks to prevent horizontal scrollbars */
  .lesson-code pre, 
  .code-window pre, 
  .article-content pre {
    white-space: pre-wrap !important;
    overflow-x: hidden !important;
    word-wrap: break-word !important;
    word-break: break-word !important;
  }
  .lesson-code pre code, 
  .code-window pre code, 
  .article-content pre code {
    white-space: pre-wrap !important;
    word-wrap: break-word !important;
    word-break: break-word !important;
    display: block;
  }
  .lesson-code pre span, 
  .code-window pre span, 
  .article-content pre span {
    display: inline !important;
    white-space: pre-wrap !important;
  }

  /* High-specificity Overrides for Sub-pages to bypass inline style sheets */
  /* About Page Overrides */
  body .about-container {
    padding: 40px 1.25rem 60px;
  }
  body .mission-block {
    grid-template-columns: 1fr;
    gap: 1.5rem;
    margin-bottom: 2.5rem;
  }
  body .mission-stats {
    grid-template-columns: 1fr;
    padding: 1.5rem;
    gap: 1.25rem;
  }
  body .values-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
    margin-bottom: 2.5rem;
  }
  body .value-card {
    padding: 1.25rem;
  }
  body .tech-grid {
    gap: 0.5rem;
  }
  body .tech-pill {
    font-size: 0.75rem;
    padding: 0.35rem 0.8rem;
  }

  /* Contact Page Overrides */
  body .contact-container {
    grid-template-columns: 1fr;
    gap: 2rem;
    padding: 40px 1.25rem 60px;
  }
  body .contact-form-card {
    padding: 1.5rem;
  }
  body .form-row {
    grid-template-columns: 1fr;
    gap: 0;
  }

  /* Blog & Blog Posts Overrides */
  body .blog-filters {
    margin-bottom: 2rem;
    gap: 0.5rem;
  }
  body .filter-btn {
    padding: 0.4rem 1rem;
    font-size: 0.8rem;
  }
  body .article-container {
    padding: 90px 1.25rem 60px;
  }
  body .article-header {
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
  }
  body .article-title {
    font-size: 1.75rem;
    margin-bottom: 1rem;
  }
  body .article-content {
    font-size: 0.95rem;
    line-height: 1.7;
  }
  body .article-content h2 {
    font-size: 1.35rem;
    margin: 2rem 0 0.75rem;
  }
  body .article-content h3 {
    font-size: 1.15rem;
    margin: 1.5rem 0 0.5rem;
  }
  body .article-content pre {
    padding: 1rem;
    margin: 1rem 0;
  }

  /* Privacy Page Overrides */
  body .policy-container {
    padding: 40px 1.25rem 60px;
  }
  body .policy-section {
    padding: 1.25rem;
    margin-bottom: 1.5rem;
  }
}

@media (max-width: 480px) {
  .features-container {
    grid-template-columns: 1fr;
  }
}

/* ── Dedicated Lessons Page & Mobile-Only View Overrides ── */
.lessons-page-content {
  padding: 1rem 0;
  flex: 1;
  display: flex;
  flex-direction: column;
}

.lessons-page-content .lesson-content-wrap {
  flex: 1;
  display: flex;
  flex-direction: column;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
  margin: 0 1rem 1.5rem;
  box-shadow: var(--shadow-card);
}

.lessons-page-content .lesson-inner {
  display: flex !important;
  flex-direction: column !important;
  grid-template-columns: none !important;
  min-height: auto !important;
}

.lessons-page-content .lesson-theory {
  border-right: none !important;
  border-bottom: 1px solid var(--border) !important;
  padding: 1.75rem 1.25rem !important;
}

.lessons-page-content .lesson-theory h3 {
  font-size: 1.3rem !important;
  font-weight: 700;
  line-height: 1.4;
  margin-bottom: 0.75rem;
  color: var(--text-primary);
}

.lessons-page-content .lesson-theory p {
  color: #e2e8f0 !important;
  font-size: 0.95rem !important;
  line-height: 1.7 !important;
  margin-bottom: 1.25rem;
}

.lessons-page-content .lesson-theory ul {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  padding-left: 0.25rem;
}

.lessons-page-content .lesson-theory ul li {
  font-size: 0.9rem !important;
  line-height: 1.6 !important;
  color: #c9d1d9 !important;
}

.lessons-page-content .lesson-code {
  background: #0d1117;
}

.lessons-page-content .lesson-code-header {
  padding: 0.75rem 1.25rem !important;
  background: #161b22;
  border-bottom: 1px solid rgba(255,255,255,0.06);
}

.lessons-page-content .lesson-code pre {
  padding: 1.25rem 1.25rem !important;
  font-size: 0.85rem !important;
  line-height: 1.6;
  overflow-x: hidden;
  margin: 0;
  font-family: var(--font-mono);
  white-space: pre-wrap !important;
  word-wrap: break-word !important;
  word-break: break-word !important;
}

.lessons-page-content .lesson-nav-buttons {
  display: flex !important;
  justify-content: space-between;
  align-items: center;
  padding: 1.25rem 1.25rem !important;
  background: rgba(0,0,0,0.2);
  border-top: 1px solid var(--border);
}

.lessons-page-content .btn-lesson-nav {
  padding: 0.6rem 1rem !important;
  font-size: 0.85rem !important;
  font-weight: 600;
  border-radius: var(--radius-sm);
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

/* ── Lessons Page Custom Header ── */
.lessons-navbar {
  background: rgba(10, 14, 19, 0.96) !important;
  backdrop-filter: blur(15px);
  border-bottom: 1px solid var(--border);
  position: sticky !important;
  top: 0 !important;
  left: auto !important;
  transform: none !important;
  width: 100% !important;
  max-width: 100% !important;
  z-index: 100;
  padding: 0 1rem !important;
}

.lessons-navbar .nav-container {
  width: 100% !important;
  display: flex !important;
  align-items: center !important;
  justify-content: space-between !important;
  gap: 0 !important;
  height: 56px !important;
  position: relative;
}

.nav-back-btn {
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  transition: background 0.2s, color 0.2s;
  background: rgba(255,255,255,0.02);
  border: 1px solid var(--border);
  z-index: 2;
}

.nav-back-btn:hover {
  background: rgba(255,255,255,0.06);
  color: var(--text-primary);
  border-color: rgba(255,255,255,0.15);
}

.nav-page-title {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: -0.3px;
  color: var(--text-primary);
  pointer-events: none;
  z-index: 1;
}

.lessons-navbar .nav-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  z-index: 2;
}

.lessons-navbar .btn-auth {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  padding: 0;
  border: 1px solid var(--border);
}

/* ── Lessons Side Navigation Overrides ── */
.btn-side-nav {
  position: fixed;
  top: 50%;
  transform: translateY(-50%);
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: rgba(17, 24, 39, 0.85) !important;
  border: 1px solid var(--border) !important;
  color: var(--text-primary) !important;
  display: inline-flex !important;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  z-index: 99;
  box-shadow: 0 4px 12px rgba(0,0,0,0.5);
  transition: all 0.2s ease-in-out;
  backdrop-filter: blur(8px);
}

.btn-side-nav:hover {
  background: var(--node-green) !important;
  color: #ffffff !important;
  border-color: var(--node-green-light) !important;
  box-shadow: 0 0 15px var(--node-green-glow);
}

.btn-side-nav:disabled {
  opacity: 0.15 !important;
  cursor: not-allowed;
  pointer-events: none;
}

.prev-side-btn {
  left: calc(50% - 240px + 12px); /* 50% screen center minus half of 480px app-container width plus 12px padding */
}

.next-side-btn {
  right: calc(50% - 240px + 12px); /* 50% screen center minus half of 480px app-container width plus 12px padding */
}

@media (max-width: 480px) {
  .prev-side-btn {
    left: 8px;
  }
  .next-side-btn {
    right: 8px;
  }
}

/* ── Continue Learning Banner ── */
.continue-learning-banner {
  background: rgba(104, 160, 99, 0.08);
  border: 1px solid rgba(104, 160, 99, 0.22);
  border-radius: var(--radius-md);
  margin: 1.25rem 1rem 0;
  padding: 0.8rem 1.1rem;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
  backdrop-filter: blur(10px);
}
.banner-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}
.banner-spark {
  font-size: 1.1rem;
  animation: pulse 1.5s infinite alternate;
}
.banner-text {
  flex: 1;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-secondary);
  line-height: 1.4;
}
.banner-text strong {
  color: var(--text-primary);
  font-weight: 700;
}
.btn-continue {
  background: var(--node-green);
  color: #fff;
  border: none;
  padding: 0.4rem 0.85rem;
  font-size: 0.75rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.2s;
  box-shadow: 0 2px 8px rgba(104, 160, 99, 0.3);
}
.btn-continue:hover {
  background: var(--node-green-light);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(104, 160, 99, 0.45);
}

/* ── Why NextSem Features Section ── */
.features-section {
  padding: 2rem 0;
  background: linear-gradient(180deg, rgba(10, 14, 19, 0) 0%, rgba(104, 160, 99, 0.02) 50%, rgba(10, 14, 19, 0) 100%);
}
.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  padding: 0 1rem;
}
.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.1rem;
  transition: transform 0.2s, border-color 0.2s;
  position: relative;
  overflow: hidden;
}
.feature-card::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, var(--node-green), var(--accent-cyan));
  opacity: 0;
  transition: opacity 0.2s;
}
.feature-card:hover {
  transform: translateY(-2px);
  border-color: rgba(104, 160, 99, 0.25);
}
.feature-card:hover::after {
  opacity: 1;
}
.feature-icon {
  font-size: 1.6rem;
  margin-bottom: 0.6rem;
}
.feature-title {
  font-size: 0.95rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.35rem;
}
.feature-desc {
  font-size: 0.78rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

@keyframes pulse {
  0% { transform: scale(1); opacity: 0.8; }
  100% { transform: scale(1.15); opacity: 1; }
}

/* ── Mobile Playground Tabs ── */
@media (max-width: 480px) {
  .playground-mobile-nav {
    display: flex;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-bottom: none;
    border-radius: var(--radius-md) var(--radius-md) 0 0;
    overflow: hidden;
  }
  .pg-m-tab {
    flex: 1;
    background: none;
    border: none;
    color: var(--text-secondary);
    padding: 0.75rem 0;
    font-size: 0.78rem;
    font-weight: 700;
    cursor: pointer;
    text-align: center;
    transition: all 0.2s;
    border-bottom: 2px solid transparent;
  }
  .pg-m-tab.active {
    color: var(--node-green);
    background: rgba(104, 160, 99, 0.05);
    border-bottom-color: var(--node-green);
  }
  
  /* Wrapper border adjustments */
  .playground-sidebar {
    border-radius: 0 0 var(--radius-md) var(--radius-md) !important;
  }
  .playground-editor {
    border-radius: 0 0 var(--radius-md) var(--radius-md) !important;
  }
  
  /* Default hide all on mobile except active tab */
  .playground-wrapper:not(.show-editor):not(.show-output) .playground-sidebar {
    display: flex !important;
  }
  .playground-wrapper:not(.show-editor):not(.show-output) .playground-editor {
    display: none !important;
  }
  
  /* Show editor tab active */
  .playground-wrapper.show-editor .playground-sidebar {
    display: none !important;
  }
  .playground-wrapper.show-editor .playground-editor {
    display: flex !important;
  }
  .playground-wrapper.show-editor .playground-editor .output-panel {
    display: none !important;
  }
  .playground-wrapper.show-editor .playground-editor .code-editor {
    border-radius: 0 0 var(--radius-md) var(--radius-md) !important;
    border-bottom: none !important;
  }
  
  /* Show output tab active */
  .playground-wrapper.show-output .playground-sidebar {
    display: none !important;
  }
  .playground-wrapper.show-output .playground-editor {
    display: flex !important;
    border: none !important;
    background: none !important;
  }
  .playground-wrapper.show-output .playground-editor .editor-header,
  .playground-wrapper.show-output .playground-editor .code-editor {
    display: none !important;
  }
  .playground-wrapper.show-output .playground-editor .output-panel {
    display: flex !important;
    flex: 1 !important;
    border: 1px solid var(--border) !important;
    border-radius: 0 0 var(--radius-md) var(--radius-md) !important;
  }
}

@media (min-width: 481px) {
  .playground-mobile-nav {
    display: none !important;
  }
}

/* ── Mobile Bottom Navigation ── */
.mobile-bottom-nav {
  position: fixed;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 480px;
  height: 60px;
  background: #0d1117;
  border-top: 1px solid var(--border);
  display: none;
  justify-content: space-around;
  align-items: center;
  z-index: 1100;
  box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.4);
}

.bottom-nav-btn {
  background: none;
  border: none;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  font-family: var(--font-sans);
  font-size: 0.65rem;
  font-weight: 600;
  gap: 3px;
  cursor: pointer;
  width: 70px;
  height: 100%;
  transition: color 0.2s;
}

.bottom-nav-btn:hover,
.bottom-nav-btn.active {
  color: var(--text-primary);
}

.bottom-nav-btn * {
  pointer-events: none;
}

.bottom-nav-btn svg {
  color: inherit;
  transition: transform 0.2s;
}

.bottom-nav-btn:active svg {
  transform: scale(0.9);
}

.profile-btn-avatar {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.05);
}

.profile-btn-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* ── Mobile Overlays ── */
.mobile-overlay {
  position: fixed;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 480px;
  bottom: 60px; /* Leave space for bottom nav bar */
  background: #070a0e;
  z-index: 1200;
  display: none;
  flex-direction: column;
  animation: slideUpOverlay 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes slideUpOverlay {
  from { transform: translateX(-50%) translateY(100%); }
  to { transform: translateX(-50%) translateY(0); }
}

.overlay-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
  background: #0d1117;
}

.overlay-header h3 {
  font-size: 1.1rem;
  font-weight: 800;
  color: var(--text-primary);
  margin: 0;
}

.close-overlay-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 1.8rem;
  line-height: 1;
  cursor: pointer;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
}

.overlay-body {
  flex: 1;
  overflow-y: auto;
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

/* Search input styling */
.search-input-wrap {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.75rem 1rem;
  transition: border-color 0.2s;
}

.search-input-wrap:focus-within {
  border-color: var(--node-green);
}

.search-input-wrap svg {
  color: var(--text-secondary);
  flex-shrink: 0;
}

.search-input-wrap input {
  background: none;
  border: none;
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  width: 100%;
  outline: none;
}

.search-results-list {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.search-result-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.85rem 1rem;
  text-decoration: none;
  transition: background 0.2s, border-color 0.2s;
}

.search-result-item:hover {
  background: rgba(104, 160, 99, 0.05);
  border-color: rgba(104, 160, 99, 0.3);
}

.search-result-info {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.search-result-title {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-primary);
}

.search-result-track {
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--node-green);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.search-result-arrow {
  color: var(--text-secondary);
}

/* User Card inside overlay */
.overlay-user-card {
  background: #0d1117;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.1rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  flex-shrink: 0;
}

/* Signed-in: horizontal avatar + name layout */
.overlay-user-info {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 0.75rem;
  text-align: left;
}

.overlay-user-avatar {
  width: 54px;
  height: 54px;
  border-radius: 50%;
  overflow: hidden;
  border: 2px solid var(--node-green);
}

.overlay-user-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.overlay-user-name {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
}

.overlay-user-email {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.btn-overlay-signout {
  background: rgba(255, 123, 114, 0.1);
  border: 1px solid rgba(255, 123, 114, 0.25);
  color: #ff7b72;
  padding: 0.5rem 1.25rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.82rem;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-overlay-signout:hover {
  background: rgba(255, 123, 114, 0.2);
}

.btn-overlay-auth {
  width: 100%;
  background: var(--node-green);
  color: #fff;
  border: none;
  padding: 0.7rem;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 0.9rem;
  cursor: pointer;
  transition: background 0.2s;
}

.btn-overlay-auth:hover {
  background: var(--node-green-light);
}

/* Menu Links inside overlay */
.overlay-menu-links {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: #0d1117;
  flex-shrink: 0;
}

.overlay-menu-link {
  display: flex;
  align-items: center;
  padding: 0.9rem 1.25rem;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 600;
  border-bottom: 1px solid var(--border);
  transition: background 0.2s, color 0.2s;
}

.overlay-menu-link:last-child {
  border-bottom: none;
}

.overlay-menu-link:hover {
  background: rgba(255, 255, 255, 0.02);
  color: var(--text-primary);
}

/* Settings section */
.overlay-settings-sec {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.1rem;
  background: #0d1117;
  flex-shrink: 0;
}

.overlay-settings-sec h4 {
  font-size: 0.82rem;
  text-transform: uppercase;
  color: var(--text-secondary);
  letter-spacing: 1px;
  margin: 0 0 0.25rem 0;
}

.settings-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.4rem 0;
  font-size: 0.9rem;
  color: var(--text-primary);
  font-weight: 600;
}

.settings-badge {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--node-green);
  background: rgba(104, 160, 99, 0.1);
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
}

/* Toggle Switch */
.switch {
  position: relative;
  display: inline-block;
  width: 40px;
  height: 22px;
}

.switch input { 
  opacity: 0;
  width: 0;
  height: 0;
}

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: #30363d;
  transition: .4s;
}

.slider:before {
  position: absolute;
  content: "";
  height: 16px;
  width: 16px;
  left: 3px;
  bottom: 3px;
  background-color: white;
  transition: .4s;
}

input:checked + .slider {
  background-color: var(--node-green);
}

input:focus + .slider {
  box-shadow: 0 0 1px var(--node-green);
}

input:checked + .slider:before {
  transform: translateX(18px);
}

.slider.round {
  border-radius: 34px;
}

.slider.round:before {
  border-radius: 50%;
}

/* Show bottom navigation on mobile */
@media (max-width: 900px) {
  .mobile-bottom-nav {
    display: flex;
  }
  
  /* Hide the top navbar completely since bottom nav handles all options now */
  .navbar, .header, .lessons-navbar {
    display: none !important;
  }

  /* Adjust padding-top on app-container since top header is gone */
  .app-container {
    padding-top: 0 !important;
    padding-bottom: 60px;
  }
  
  /* Also lessons and playground should adjust their layout if needed */
  #view-content {
    top: 0 !important;
    min-height: calc(100vh - 60px) !important; /* only bottom nav remains */
  }
}


/* ── Light Mode (toggled via mobile menu Settings) ── */
body.light-mode {
  background: #f0f4f8;
  --bg-dark: #ffffff;
  --bg-card: #f7fafc;
  --bg-card2: #edf2f7;
  --bg-glass: rgba(0,0,0,0.03);
  --border: rgba(0,0,0,0.1);
  --border-hover: rgba(104,160,99,0.5);
  --text-primary: #1a202c;
  --text-secondary: #4a5568;
  --text-muted: #718096;
}
body.light-mode .app-container { background: #fff; box-shadow: 0 0 40px rgba(0,0,0,0.12); }
body.light-mode .mobile-bottom-nav { background: #fff; border-top: 1px solid rgba(0,0,0,0.1); }
body.light-mode .mobile-overlay { background: #f7fafc; }
body.light-mode .overlay-header { background: #fff; border-bottom: 1px solid rgba(0,0,0,0.08); }
body.light-mode .overlay-user-card,
body.light-mode .overlay-menu-links,
body.light-mode .overlay-settings-sec { background: #fff; border-color: rgba(0,0,0,0.08); }
body.light-mode .overlay-menu-link { color: #4a5568; }
body.light-mode .overlay-menu-link:hover { background: rgba(0,0,0,0.03); color: #1a202c; }
body.light-mode .settings-item { color: #1a202c; }
body.light-mode .search-input-wrap { background: #fff; border-color: rgba(0,0,0,0.1); }
body.light-mode .search-input-wrap input { color: #1a202c; }
body.light-mode .search-result-item { background: #fff; border-color: rgba(0,0,0,0.08); }
body.light-mode .swipe-card,
body.light-mode .sc-body,
body.light-mode .sc-footer,
body.light-mode .sc-swipe-hint { background: #fff; }
body.light-mode .track-filter-strip { background: #f7fafc; border-bottom-color: rgba(0,0,0,0.08); }
body.light-mode .page-hero { color: #1a202c; }
body.light-mode .sc-swipe-hint { background: #fff; }
body.light-mode .track-filter-strip { background: #f7fafc; border-bottom-color: rgba(0,0,0,0.08); }
body.light-mode .page-hero { color: #1a202c; }
body.light-mode .footer { background: #f0f4f8; border-top: 1px solid rgba(0,0,0,0.1); }

/* ── Global Mobile Fixes (no top navbar) ── */
/* Ensure all pages have bottom padding so content clears the 60px bottom nav */
@media (max-width: 900px) {
  .app-container {
    padding-bottom: 72px !important; /* 60px nav + 12px buffer */
  }

  /* Section / hero padding for pages without top navbar */
  .section-header { padding: 2rem 1.25rem 1rem; }
  .section-title { font-size: clamp(1.4rem, 5vw, 2rem); }
  .section-desc { font-size: 0.9rem; }

  /* Module / curriculum cards */
  .module-card { padding: 1.1rem !important; }
  .module-title { font-size: 1rem !important; }

  /* Footer spacing */
  .footer { padding: 1.5rem 1.25rem !important; margin-bottom: 0; }

  /* Fix hero section top padding since there is no top navbar any more */
  section.hero, .hero-section {
    padding-top: 2.5rem !important;
  }

  /* Track cards on home */
  .tracks-grid {
    grid-template-columns: 1fr !important;
    gap: 0.85rem !important;
  }

  /* Blog post content pages */
  .post-hero { padding: 2rem 1.25rem 1.5rem !important; }
  .post-container { padding: 1.5rem 1.25rem 6rem !important; }
  .post-hero h1 { font-size: clamp(1.4rem, 5vw, 2rem) !important; }
}

/* ── Top-Right User Sidebar ── */
.sidebar-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(5, 8, 12, 0.6);
  backdrop-filter: blur(8px);
  z-index: 1500;
  display: none;
  opacity: 0;
  transition: opacity 0.3s ease;
}
.sidebar-backdrop.active {
  display: block;
  opacity: 1;
}

.user-sidebar {
  position: fixed;
  top: 0;
  right: 0;
  width: 340px;
  max-width: 85%;
  height: 100%;
  background: #0d1117;
  border-left: 1px solid var(--border);
  z-index: 1600;
  transform: translateX(100%);
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  display: flex;
  flex-direction: column;
  box-shadow: -10px 0 40px rgba(0, 0, 0, 0.6);
}
.user-sidebar.open {
  transform: translateX(0);
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--border);
  background: #111827;
}
.sidebar-header h3 {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--text-primary);
  margin: 0;
}
.sidebar-close-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 1.8rem;
  cursor: pointer;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  transition: color 0.2s;
}
.sidebar-close-btn:hover {
  color: var(--text-primary);
}

.sidebar-body {
  flex: 1;
  overflow-y: auto;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

/* Logged Out View */
.sidebar-logged-out {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  align-items: center;
  text-align: center;
}
.welcome-box {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  width: 100%;
}
.welcome-box h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}
.welcome-box p {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin: 0;
}

.sidebar-logged-out .google-sign-in-btn {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.88rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.25s;
}
.sidebar-logged-out .google-sign-in-btn:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.2);
}

.sidebar-divider {
  display: flex;
  align-items: center;
  width: 100%;
  color: var(--text-muted);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 1px;
}
.sidebar-divider::before, .sidebar-divider::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border);
}
.sidebar-divider::before { margin-right: 12px; }
.sidebar-divider::after { margin-left: 12px; }

.sidebar-email-btn {
  width: 100%;
  background: var(--node-green);
  border: none;
  color: #fff;
  font-family: var(--font-sans);
  font-weight: 700;
  font-size: 0.88rem;
  padding: 0.75rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background 0.2s;
}
.sidebar-email-btn:hover {
  background: var(--node-green-light);
}

/* Logged In View */
.sidebar-logged-in {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}
.sidebar-user-card {
  display: flex;
  align-items: center;
  gap: 1rem;
  background: #111827;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1rem;
}
.sidebar-user-avatar {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--node-green);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.25rem;
  border: 1px solid var(--border);
}
.sidebar-user-avatar img {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
}
.sidebar-user-info {
  display: flex;
  flex-direction: column;
  min-width: 0;
}
.sidebar-username {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.sidebar-user-email {
  font-size: 0.75rem;
  color: var(--text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.sidebar-progress-sec {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.progress-lbl-row {
  display: flex;
  justify-content: space-between;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-secondary);
}
.sidebar-pb-wrap {
  height: 6px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 3px;
  overflow: hidden;
}
.sidebar-pb-fill {
  height: 100%;
  background: var(--node-green);
  border-radius: 3px;
  transition: width 0.4s ease;
}

.sidebar-menu-items {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
}
.sidebar-menu-item {
  display: flex;
  align-items: center;
  padding: 0.8rem 1rem;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 600;
  border-bottom: 1px solid var(--border);
  transition: all 0.2s;
}
.sidebar-menu-item:last-child {
  border-bottom: none;
}
.sidebar-menu-item:hover {
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-primary);
}

.btn-sidebar-signout {
  width: 100%;
  background: rgba(255, 123, 114, 0.1);
  border: 1px solid rgba(255, 123, 114, 0.25);
  color: #ff7b72;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.85rem;
  padding: 0.7rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.2s;
  margin-top: auto;
}
.btn-sidebar-signout:hover {
  background: rgba(255, 123, 114, 0.2);
}

/* Floating top right action bar on desktop */
.floating-top-actions {
  position: fixed;
  top: 16px;
  right: calc(50vw - 220px); /* Positioned top right of the 480px centered container */
  z-index: 950;
  display: flex;
  align-items: center;
  gap: 12px;
}
/* Adjust floating position on very narrow screens */
@media (max-width: 480px) {
  .floating-top-actions {
    right: 16px;
  }
}
/* Hide floating top actions on mobile when bottom navigation is visible */
@media (max-width: 900px) {
  .floating-top-actions {
    display: none !important;
  }
}

/* Light mode support for User Sidebar */
body.light-mode .user-sidebar {
  background: #ffffff;
  border-left-color: rgba(0, 0, 0, 0.1);
}
body.light-mode .sidebar-header {
  background: #f7fafc;
  border-bottom-color: rgba(0, 0, 0, 0.08);
}
body.light-mode .sidebar-user-card {
  background: #f7fafc;
  border-color: rgba(0, 0, 0, 0.08);
}
body.light-mode .welcome-box,
body.light-mode .sidebar-progress-sec,
body.light-mode .sidebar-menu-items {
  background: #ffffff;
  border-color: rgba(0, 0, 0, 0.08);
}
body.light-mode .sidebar-menu-item {
  color: #4a5568;
  border-bottom-color: rgba(0, 0, 0, 0.08);
}
body.light-mode .sidebar-menu-item:hover {
  background: rgba(0, 0, 0, 0.03);
  color: #1a202c;
}
body.light-mode .sidebar-logged-out .google-sign-in-btn {
  background: #ffffff;
  border-color: rgba(0, 0, 0, 0.1);
  color: #1a202c;
}
body.light-mode .sidebar-logged-out .google-sign-in-btn:hover {
  background: rgba(0, 0, 0, 0.03);
}

/* ── Homepage Swipe System ── */
#index-swipe-container {
  position: fixed;
  top: 0;
  bottom: 60px; /* leaves room for bottom navigation */
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 480px;
  overflow: hidden;
  touch-action: none;
  background: var(--bg-dark);
  z-index: 10;
}

#index-swipe-container .swipe-card {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 2.2rem 1.5rem;
  background: var(--bg-dark);
  will-change: transform, opacity;
  transition: transform 0.38s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.38s ease;
  overflow-y: auto;
  user-select: none;
  -webkit-user-select: none;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

#index-swipe-container .swipe-card.sc-active {
  transform: translate3d(0, 0, 0);
  z-index: 2;
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

#index-swipe-container .swipe-card.sc-prev {
  transform: translate3d(0, -100%, 0);
  z-index: 1;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

#index-swipe-container .swipe-card.sc-next {
  transform: translate3d(0, 100%, 0);
  z-index: 1;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

#index-swipe-container .swipe-card h2 {
  font-size: 1.6rem;
  font-weight: 900;
  letter-spacing: -0.8px;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

/* Feature & Track Lists for Homepage Cards */
.features-scroll-wrap, .tracks-list {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  margin: 1rem 0;
  text-align: left;
}

.feature-item, .track-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.1rem;
  transition: var(--transition);
  cursor: pointer;
}

.feature-item h4, .track-item h4 {
  margin: 0 0 0.25rem 0;
  font-size: 0.95rem;
  font-weight: 800;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.feature-item p, .track-item p {
  margin: 0;
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.feature-item:hover, .track-item:hover {
  border-color: var(--border-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-card);
}

/* Mini Sandbox Teaser styles */
.mini-sandbox {
  width: 100%;
  background: #0b0f14;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  display: flex;
  flex-direction: column;
  text-align: left;
  overflow: hidden;
  box-shadow: var(--shadow-card);
}

.mini-sandbox .code-header {
  background: #11161d;
  margin: 0;
  padding: 0.5rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-muted);
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.mini-sandbox .mini-editor {
  background: none;
  border: none;
  resize: none;
  color: #c9d1d9;
  font-family: var(--font-mono);
  font-size: 0.88rem;
  padding: 1rem;
  height: 100px;
  line-height: 1.6;
  outline: none;
}

.mini-sandbox .btn-run {
  margin: 0 1rem 1rem;
  align-self: flex-end;
  background: rgba(104, 160, 99, 0.15);
  border: 1px solid var(--node-green);
  color: var(--node-green-light);
  font-weight: 700;
  padding: 0.45rem 1.1rem;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  transition: var(--transition);
}

.mini-sandbox .btn-run:hover {
  background: var(--node-green);
  color: #fff;
  box-shadow: 0 2px 12px rgba(104, 160, 99, 0.3);
}

.mini-sandbox .mini-console {
  background: #05070a;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  padding: 0.75rem 1rem;
  min-height: 50px;
  max-height: 100px;
  overflow-y: auto;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--node-green-light);
}

/* Profile Card Styling on Card 5 */
.profile-teaser-card {
  width: 100%;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  text-align: left;
  box-shadow: var(--shadow-card);
}

.profile-teaser-card h3 {
  margin: 0;
  font-size: 1.2rem;
  font-weight: 900;
  color: var(--text-primary);
}

.profile-progress-row {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.profile-progress-meta {
  display: flex;
  justify-content: space-between;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--text-secondary);
}

.profile-progress-bar {
  height: 8px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 4px;
  overflow: hidden;
}

.profile-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--node-green), #4e9646);
  width: 0%;
  transition: width 0.5s ease;
}

/* Light mode overrides for Homepage swipe components */
body.light-mode #index-swipe-container {
  background: #ffffff;
}

body.light-mode #index-swipe-container .swipe-card {
  background: #ffffff;
}

body.light-mode .feature-item, 
body.light-mode .track-item,
body.light-mode .profile-teaser-card {
  background: #f7fafc;
  border-color: rgba(0, 0, 0, 0.08);
}

body.light-mode .mini-sandbox {
  background: #f6f8fa;
  border-color: rgba(0, 0, 0, 0.08);
}

body.light-mode .mini-sandbox .code-header {
  background: #eaeef2;
  border-bottom-color: rgba(0, 0, 0, 0.06);
}

body.light-mode .mini-sandbox .mini-editor {
  color: #24292f;
}

body.light-mode .mini-sandbox .mini-console {
  background: #24292f;
  color: #7ee787;
}

/* ── PWA Custom Install Banner ── */
.pwa-install-banner {
  position: fixed;
  bottom: 80px;
  left: 50%;
  transform: translateX(-50%) translateY(150%);
  width: calc(100% - 2rem);
  max-width: 400px;
  background: rgba(22, 27, 34, 0.9);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  box-shadow: var(--shadow-lg), 0 10px 40px rgba(0, 0, 0, 0.5);
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

.pwa-install-banner.show {
  transform: translateX(-50%) translateY(0);
}

.pwa-banner-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.pwa-banner-icon {
  width: 42px;
  height: 42px;
  border-radius: 10px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.pwa-banner-title {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.pwa-banner-title h4 {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
}

.pwa-banner-title p {
  margin: 0;
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.pwa-banner-actions {
  display: flex;
  gap: 0.75rem;
}

.pwa-btn-install {
  flex: 1;
  background: var(--node-green);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  padding: 0.6rem;
  font-size: 0.85rem;
  font-weight: 700;
  cursor: pointer;
  transition: filter 0.2s;
}

.pwa-btn-install:hover {
  filter: brightness(1.1);
}

.pwa-btn-dismiss {
  flex: 0.6;
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.6rem;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.pwa-btn-dismiss:hover {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
}

/* ── PWA Menu Item styling inside Overlay ── */
.menu-install-pwa-wrap {
  margin: 0.5rem 0 1rem 0;
}

.btn-install-pwa {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background: linear-gradient(135deg, var(--node-green), var(--node-green-light));
  color: #fff;
  border: none;
  padding: 0.75rem;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-install-pwa:hover {
  filter: brightness(1.1);
  transform: translateY(-1px);
}

/* ── Desktop Sidebar TOC Styles ── */
.desktop-only-sidebar {
  display: none;
}

@media (min-width: 901px) {
  #view-content {
    flex-direction: row !important;
    overflow-y: hidden !important; /* Main column scrolls independently */
  }
  .desktop-only-sidebar {
    display: flex !important;
    width: 280px;
    background: var(--bg-card);
    border-right: 1px solid var(--border);
    flex-direction: column;
    height: 100%;
    flex-shrink: 0;
  }
  #lesson-detail-main-col {
    flex: 1;
    display: flex;
    flex-direction: column;
    height: 100%;
    overflow-y: auto !important;
  }
  .sidebar-toc-list::-webkit-scrollbar {
    width: 3px;
  }
  .sidebar-toc-list::-webkit-scrollbar-track {
    background: transparent;
  }
  .sidebar-toc-list::-webkit-scrollbar-thumb {
    background: rgba(104, 160, 99, 0.2);
    border-radius: 3px;
  }
}

/* ── Complete & Next Button Celebratory Style ── */
.bn-complete-btn {
  background: var(--node-green) !important;
  border-color: var(--node-green) !important;
  color: #fff !important;
  box-shadow: 0 2px 10px rgba(104, 160, 99, 0.35) !important;
  font-weight: 800 !important;
}
.bn-complete-btn:hover {
  filter: brightness(1.1);
  transform: translateY(-1px);
}

/* ── Confetti Canvas ── */
#confetti-canvas {
  pointer-events: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 999999;
}

/* ── Vertical Swiper Track & Recycle Slides ── */
.swipe-container .slider-track {
  display: flex;
  flex-direction: column;
  width: 100%;
  height: 300%;
  position: absolute;
  top: -100%;
  left: 0;
  transform: translate3d(0, 0, 0);
  will-change: transform;
}

.swipe-container .slide {
  width: 100%;
  height: 33.33333%;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 16px;
  overflow-y: auto;
  touch-action: pan-x;
}

/* ── Swipe Card Sizing and Inner Scroll ── */
.swipe-container .slide .card {
  background-color: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  width: 100%;
  max-width: 600px;
  height: 88%;
  max-height: 92%;
  padding: 24px;
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.3);
  display: flex;
  flex-direction: column;
  gap: 16px;
  overflow-y: auto;
  position: relative;
}

.card-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

@media (max-width: 768px) {
  .swipe-container .slide {
    padding: 12px 10px;
  }
  .swipe-container .slide .card {
    height: 94%;
    padding: 20px 18px;
    gap: 14px;
    border-radius: 12px;
  }
}

/* Style scrollbars for cards and code blocks */
.swipe-container .slide .card::-webkit-scrollbar {
  width: 5px;
  height: 5px;
}
.swipe-container .slide .card::-webkit-scrollbar-track {
  background: rgba(0, 0, 0, 0.15);
  border-radius: 99px;
}
.swipe-container .slide .card::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.15);
  border-radius: 99px;
}
.swipe-container .slide .card::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.3);
}

.swipe-container .slide .card {
  scrollbar-width: thin;
  scrollbar-color: rgba(255, 255, 255, 0.15) rgba(0, 0, 0, 0.15);
}

/* ── Run Button & Console Box Styles ── */
.swipe-container .run-btn {
  background: linear-gradient(135deg, var(--node-green), var(--node-green-light));
  color: white;
  border: none;
  padding: 8px 14px;
  border-radius: 6px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.78rem;
  margin-top: 4px;
  transition: opacity 0.2s;
  width: fit-content;
}
.swipe-container .run-btn:hover {
  opacity: 0.9;
}
.terminal-box {
  background-color: #060913;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--node-green-light);
  margin-top: 10px;
  line-height: 1.5;
  display: none;
  text-align: left;
  width: 100%;
  max-height: 180px;
  overflow-y: auto;
  scroll-behavior: smooth;
  box-sizing: border-box;
}
.terminal-box.active {
  display: block;
  border-color: rgba(104, 160, 99, 0.4);
  box-shadow: 0 4px 12px rgba(104, 160, 99, 0.1);
  animation: fadeInTerminal 0.25s ease-out;
}

@keyframes fadeInTerminal {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ── Interactive Guided Tour Styles ── */
.tour-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(10, 14, 19, 0.4);
  z-index: 100000;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease;
}
.tour-backdrop.active {
  opacity: 1;
  pointer-events: auto;
}
.tour-tooltip {
  position: fixed;
  background: #161b22;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  width: 280px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  z-index: 100005;
  opacity: 0;
  pointer-events: none;
  transform: scale(0.95);
  transition: opacity 0.2s ease, transform 0.2s ease, top 0.25s ease, left 0.25s ease;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.tour-tooltip.active {
  opacity: 1;
  pointer-events: auto;
  transform: scale(1);
}
.tour-tooltip h4 {
  margin: 0;
  font-size: 0.92rem;
  font-weight: 800;
  color: var(--node-green-light);
}
.tour-tooltip p {
  margin: 0;
  font-size: 0.8rem;
  line-height: 1.4;
  color: #a8b5c2;
}
.tour-tooltip-actions {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 4px;
}
.tour-btn-skip {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  padding: 4px 8px;
}
.tour-btn-skip:hover {
  color: var(--text-primary);
}
.tour-btn-nav-group {
  display: flex;
  gap: 6px;
}
.tour-btn-back, .tour-btn-next {
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 10px;
  font-size: 0.75rem;
  font-weight: 700;
  cursor: pointer;
}
.tour-btn-back {
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-secondary);
}
.tour-btn-back:hover {
  background: rgba(255, 255, 255, 0.08);
}
.tour-btn-next {
  background: var(--node-green);
  color: white;
  border-color: var(--node-green);
}
.tour-btn-next:hover {
  filter: brightness(1.1);
}
.tour-highlight {
  position: relative !important;
  z-index: 100002 !important;
  box-shadow: 0 0 0 9999px rgba(10, 14, 19, 0.8), 0 0 20px rgba(104, 160, 99, 0.5) !important;
  pointer-events: none !important;
}

@keyframes stackIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero-feature-card:hover {
  background: rgba(104, 160, 99, 0.08) !important;
  border-color: rgba(104, 160, 99, 0.4) !important;
  transform: translateY(-2px);
}

.scroll-hint-wrapper {
  position: relative;
  width: 100%;
}
.scroll-hint-arrow-left,
.scroll-hint-arrow-right {
  position: absolute;
  top: 0;
  height: 100%;
  width: 44px;
  display: flex;
  align-items: center;
  color: rgba(255, 255, 255, 0.4);
  pointer-events: auto;
  cursor: pointer;
  border: none;
  outline: none;
  z-index: 100;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}
.scroll-hint-arrow-left {
  left: 0;
  background: linear-gradient(to right, var(--bg-dark) 45%, transparent);
  justify-content: flex-start;
  padding-left: 8px;
}
.scroll-hint-arrow-right {
  right: 0;
  background: linear-gradient(to left, var(--bg-dark) 45%, transparent);
  justify-content: flex-end;
  padding-right: 8px;
}
.scroll-hint-arrow-left:hover {
  color: var(--node-green-light);
  transform: translateX(-2px);
  background: linear-gradient(to right, var(--bg-dark) 60%, transparent);
}
.scroll-hint-arrow-right:hover {
  color: var(--node-green-light);
  transform: translateX(2px);
  background: linear-gradient(to left, var(--bg-dark) 60%, transparent);
}

body.light-mode .scroll-hint-arrow-left {
  background: linear-gradient(to right, #ffffff 45%, transparent);
  color: rgba(0, 0, 0, 0.35);
}
body.light-mode .scroll-hint-arrow-right {
  background: linear-gradient(to left, #ffffff 45%, transparent);
  color: rgba(0, 0, 0, 0.35);
}
body.light-mode .scroll-hint-arrow-left:hover {
  background: linear-gradient(to right, #ffffff 60%, transparent);
  color: var(--node-green);
}
body.light-mode .scroll-hint-arrow-right:hover {
  background: linear-gradient(to left, #ffffff 60%, transparent);
  color: var(--node-green);
}

.s-tag-btn {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border);
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  font-family: var(--font-heading);
}

.s-tag-btn:hover {
  background: rgba(104, 160, 99, 0.08) !important;
  border-color: rgba(104, 160, 99, 0.4) !important;
  color: var(--node-green-light) !important;
}

body.light-mode .s-tag-btn {
  background: rgba(0, 0, 0, 0.02);
  color: var(--text-primary);
}

body.sv .mobile-bottom-nav {
  display: none !important;
}

body.sv #view-content {
  bottom: 0 !important;
}

body.sv .lbn {
  padding-bottom: calc(0.75rem + env(safe-area-inset-bottom, 0px)) !important;
}

#detail-terminal {
  background-color: #060913 !important;
  border: none !important;
  border-top: 1px solid rgba(104, 160, 99, 0.3) !important;
  border-radius: 0 0 var(--radius-sm) var(--radius-sm) !important;
  margin: 0 !important;
  padding: 12px 14px !important;
  box-shadow: none !important;
  max-height: 180px;
  overflow-y: auto;
  scroll-behavior: smooth;
  box-sizing: border-box;
}

#detail-terminal:not(.active) {
  display: none !important;
}

#detail-terminal.active {
  display: block !important;
  animation: fadeInTerminal 0.25s ease-out;
}

/* ── Mobile Menu Overlay Progress Bar & Completed Cards ── */
.overlay-progress-section {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin: 12px 0;
  width: 100%;
}
.overlay-progress-label-row {
  display: flex;
  justify-content: space-between;
  font-size: 0.76rem;
  font-weight: 700;
  color: var(--text-secondary);
}
.overlay-pb-wrap {
  height: 8px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 4px;
  overflow: hidden;
  width: 100%;
}
.overlay-pb-fill {
  height: 100%;
  background: linear-gradient(90deg, #10b981, #00d4aa);
  border-radius: 4px;
  transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 0 10px rgba(16, 185, 129, 0.5);
}
.sidebar-pb-fill {
  background: linear-gradient(90deg, #10b981, #00d4aa) !important;
  box-shadow: 0 0 10px rgba(16, 185, 129, 0.5) !important;
}
.card.completed {
  border-color: rgba(16, 185, 129, 0.35) !important;
  background: linear-gradient(135deg, #111827 0%, rgba(16, 185, 129, 0.04) 100%) !important;
  box-shadow: 0 12px 40px rgba(16, 185, 129, 0.05) !important;
  position: relative;
}
.card.completed::before {
  content: '✓';
  position: absolute;
  top: 12px;
  right: 12px;
  width: 20px;
  height: 20px;
  background: rgba(16, 185, 129, 0.15);
  border: 1px solid rgba(16, 185, 129, 0.4);
  color: #34d399;
  border-radius: 50%;
  font-size: 0.72rem;
  font-weight: 900;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 10px rgba(16, 185, 129, 0.3);
  z-index: 10;
}



/* Gamified Buttons */
.btn-primary, .btn-ghost, .btn-notebook, .btn-swiper-lessons, .btn-syllabus, .btn-run, .btn-continue, .google-sign-in-btn, .auth-submit-btn {
  border-radius: var(--radius-xl) !important;
  box-shadow: 0 4px 0 0 rgba(0,0,0,0.3) !important;
  transition: transform 0.1s, box-shadow 0.1s !important;
}
.btn-primary:active, .btn-ghost:active, .btn-notebook:active, .btn-swiper-lessons:active, .btn-syllabus:active, .btn-run:active, .btn-continue:active, .google-sign-in-btn:active, .auth-submit-btn:active {
  transform: translateY(4px) !important;
  box-shadow: 0 0 0 0 rgba(0,0,0,0.3) !important;
}

/* Light Mode Overrides for shadows */
body.light-mode .btn-primary, 
body.light-mode .btn-ghost, 
body.light-mode .btn-notebook, 
body.light-mode .btn-swiper-lessons, 
body.light-mode .btn-syllabus, 
body.light-mode .btn-run, 
body.light-mode .btn-continue, 
body.light-mode .google-sign-in-btn, 
body.light-mode .auth-submit-btn {
  box-shadow: 0 4px 0 0 rgba(0,0,0,0.15) !important;
}
body.light-mode .btn-primary:active, 
body.light-mode .btn-ghost:active, 
body.light-mode .btn-notebook:active, 
body.light-mode .btn-swiper-lessons:active, 
body.light-mode .btn-syllabus:active, 
body.light-mode .btn-run:active, 
body.light-mode .btn-continue:active, 
body.light-mode .google-sign-in-btn:active, 
body.light-mode .auth-submit-btn:active {
  box-shadow: 0 0 0 0 rgba(0,0,0,0.15) !important;
  transform: translateY(4px) !important;
}


/* Gamified Cards */
.swipe-card, .hero-feature-card, .card {
  border-radius: 24px !important;
  box-shadow: var(--shadow-card) !important;
}