/* =====================================================
   style.css — Ravionus Learn Platform Design System
   ===================================================== */

/* ── Google Font ── */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;500&display=swap');

/* ── Design Tokens ── */
:root {
  /* Colors */
  --bg-primary:    #0a0a0f;
  --bg-secondary:  #111118;
  --bg-card:       #16161f;
  --bg-card-hover: #1e1e2a;
  --bg-glass:      rgba(255,255,255,0.04);
  --bg-glass-hover:rgba(255,255,255,0.07);

  --border:        rgba(255,255,255,0.08);
  --border-bright: rgba(255,255,255,0.16);

  --text-primary:  #f0f0f8;
  --text-secondary:#9090a8;
  --text-muted:    #55556a;

  --accent:        #7c3aed;
  --accent-glow:   rgba(124,58,237,0.25);
  --accent-light:  #a855f7;
  --green:         #22c55e;
  --green-bg:      rgba(34,197,94,0.12);
  --red:           #ef4444;
  --red-bg:        rgba(239,68,68,0.12);
  --amber:         #f59e0b;
  --amber-bg:      rgba(245,158,11,0.1);
  --blue:          #3b82f6;
  --blue-bg:       rgba(59,130,246,0.1);

  /* Spacing */
  --radius-sm:  8px;
  --radius:     14px;
  --radius-lg:  20px;
  --radius-xl:  28px;

  /* Timing */
  --transition: 0.2s ease;
  --transition-slow: 0.4s ease;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', system-ui, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

/* ── Scrollbar ── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb { background: var(--border-bright); border-radius: 99px; }

/* ── Typography ── */
h1, h2, h3, h4 { font-weight: 700; line-height: 1.2; letter-spacing: -0.02em; }
h1 { font-size: clamp(2rem, 5vw, 3.2rem); }
h2 { font-size: clamp(1.4rem, 3vw, 1.9rem); }
h3 { font-size: 1.15rem; font-weight: 600; margin: 1.2em 0 0.5em; }
p  { margin-bottom: 1em; color: var(--text-secondary); }
ul, ol { padding-left: 1.5em; color: var(--text-secondary); margin-bottom: 1em; }
li { margin-bottom: 0.4em; }
code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.88em;
  background: rgba(255,255,255,0.07);
  border: 1px solid var(--border);
  padding: 0.1em 0.4em;
  border-radius: 5px;
  color: var(--accent-light);
}
strong { color: var(--text-primary); font-weight: 600; }

/* ── Layout ── */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ── NAV ── */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10,10,15,0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
}
.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-weight: 800;
  font-size: 1.1rem;
  color: var(--text-primary);
  letter-spacing: -0.03em;
}
.nav-logo .logo-badge {
  background: linear-gradient(135deg, var(--accent), var(--accent-light));
  color: #fff;
  font-size: 0.7rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 99px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}
.nav-back {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: color var(--transition);
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  background: var(--bg-glass);
  border: 1px solid var(--border);
}
.nav-back:hover { color: var(--text-primary); background: var(--bg-glass-hover); }

/* ── Hero Section ── */
.hero {
  padding: 80px 24px 60px;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -120px; left: 50%;
  transform: translateX(-50%);
  width: 600px; height: 600px;
  background: radial-gradient(ellipse, var(--accent-glow) 0%, transparent 70%);
  pointer-events: none;
}
.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--bg-glass);
  border: 1px solid var(--border-bright);
  color: var(--accent-light);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 6px 16px;
  border-radius: 99px;
  margin-bottom: 24px;
}
.hero h1 {
  margin-bottom: 20px;
}
.hero h1 .gradient-text {
  background: linear-gradient(135deg, var(--accent-light), #60a5fa);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-sub {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto 40px;
}
.hero-stats {
  display: flex;
  justify-content: center;
  gap: 40px;
  flex-wrap: wrap;
}
.stat {
  text-align: center;
}
.stat-value {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.03em;
}
.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ── Search Bar ── */
.search-bar {
  max-width: 480px;
  margin: 0 auto 48px;
  padding: 0 24px;
}
.search-input-wrap {
  position: relative;
  display: flex;
  align-items: center;
}
.search-icon {
  position: absolute;
  left: 16px;
  color: var(--text-muted);
  font-size: 1rem;
}
.search-input {
  width: 100%;
  padding: 14px 20px 14px 44px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.95rem;
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
}
.search-input::placeholder { color: var(--text-muted); }
.search-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

/* ── Topic Grid ── */
.topics-section {
  padding: 0 24px 80px;
}
.section-header {
  max-width: 1200px;
  margin: 0 auto 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.section-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.topics-grid {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 20px;
}

/* ── Topic Card ── */
.topic-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 28px;
  cursor: pointer;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  gap: 16px;
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition), background var(--transition);
  position: relative;
  overflow: hidden;
}
.topic-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: var(--card-color, var(--accent));
  opacity: 0;
  transition: opacity var(--transition);
}
.topic-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-bright);
  box-shadow: 0 20px 60px rgba(0,0,0,0.4);
  background: var(--bg-card-hover);
}
.topic-card:hover::before { opacity: 1; }

.card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}
.card-icon {
  width: 52px; height: 52px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  background: var(--bg-glass);
  border: 1px solid var(--border);
  flex-shrink: 0;
}
.card-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: flex-end;
}
.badge {
  font-size: 0.72rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 99px;
  letter-spacing: 0.03em;
}
.badge-difficulty-Beginner { background: var(--green-bg); color: var(--green); }
.badge-difficulty-Intermediate { background: var(--amber-bg); color: var(--amber); }
.badge-difficulty-Advanced { background: var(--red-bg); color: var(--red); }
.badge-time { background: var(--bg-glass); color: var(--text-muted); border: 1px solid var(--border); }
.badge-completed { background: var(--green-bg); color: var(--green); }

.card-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
  letter-spacing: -0.02em;
}
.card-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0;
}
.card-tags {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.tag {
  font-size: 0.75rem;
  color: var(--text-muted);
  background: var(--bg-glass);
  border: 1px solid var(--border);
  padding: 2px 10px;
  border-radius: 99px;
}
.card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: auto;
}
.progress-wrap {
  flex: 1;
  margin-right: 16px;
}
.progress-bar {
  height: 4px;
  background: var(--border);
  border-radius: 99px;
  overflow: hidden;
  margin-top: 4px;
}
.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent-light));
  border-radius: 99px;
  transition: width 0.5s ease;
}
.progress-label {
  font-size: 0.75rem;
  color: var(--text-muted);
}
.card-arrow {
  color: var(--text-muted);
  font-size: 1.2rem;
  transition: transform var(--transition), color var(--transition);
}
.topic-card:hover .card-arrow { transform: translateX(4px); color: var(--text-primary); }

/* ── Empty State ── */
.empty-state {
  text-align: center;
  padding: 60px 24px;
  color: var(--text-muted);
}
.empty-state .empty-icon { font-size: 3rem; margin-bottom: 12px; }

/* ======================================================
   TOPIC / LESSON PAGE
   ====================================================== */

/* ── Topic Hero ── */
.topic-hero {
  padding: 48px 24px 40px;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, rgba(124,58,237,0.04) 0%, transparent 100%);
}
.topic-hero-inner {
  max-width: 900px;
  margin: 0 auto;
}
.topic-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}
.topic-icon-lg {
  font-size: 2.5rem;
}
.topic-title {
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  margin: 0 0 12px;
}
.topic-desc-hero {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 680px;
  margin: 0;
}

/* ── Main Reader Layout ── */
.reader-layout {
  max-width: 1100px;
  margin: 0 auto;
  padding: 40px 24px 80px;
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 40px;
  align-items: start;
}

/* ── Progress Sidebar ── */
.progress-sidebar {
  position: sticky;
  top: 84px;
}
.sidebar-title {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 16px;
}
.section-steps {
  display: flex;
  flex-direction: column;
  gap: 0;
  position: relative;
}
.section-steps::before {
  content: '';
  position: absolute;
  left: 15px; top: 0; bottom: 0;
  width: 2px;
  background: var(--border);
}
.step-item {
  position: relative;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 8px 12px 8px 44px;
  border-radius: var(--radius-sm);
  cursor: default;
  transition: background var(--transition);
}
.step-item.completed { cursor: pointer; }
.step-item.completed:hover { background: var(--bg-glass); }
.step-dot {
  position: absolute;
  left: 9px;
  width: 14px; height: 14px;
  border-radius: 50%;
  background: var(--border);
  border: 2px solid var(--bg-primary);
  z-index: 1;
  transition: background var(--transition), box-shadow var(--transition);
}
.step-item.completed .step-dot {
  background: var(--green);
  box-shadow: 0 0 8px rgba(34,197,94,0.4);
}
.step-item.active .step-dot {
  background: var(--accent);
  box-shadow: 0 0 10px var(--accent-glow);
  animation: pulse-dot 2s infinite;
}
.step-item.quiz-type .step-dot { background: var(--amber); }
.step-item.quiz-type.completed .step-dot { background: var(--green); }
@keyframes pulse-dot {
  0%, 100% { box-shadow: 0 0 10px var(--accent-glow); }
  50% { box-shadow: 0 0 20px rgba(124,58,237,0.6); }
}
.step-label {
  font-size: 0.82rem;
  color: var(--text-muted);
  line-height: 1.3;
  transition: color var(--transition);
}
.step-item.active .step-label { color: var(--text-primary); font-weight: 600; }
.step-item.completed .step-label { color: var(--text-secondary); }
.step-type-icon { font-size: 0.75rem; }

/* ── Lesson Content Area ── */
.content-area {
  min-width: 0;
}
.section-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  overflow: hidden;
  animation: fadeUp 0.35s ease;
}
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}
.section-card-header {
  padding: 28px 32px 20px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 12px;
}
.section-type-badge {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 4px 12px;
  border-radius: 99px;
}
.type-lesson { background: var(--blue-bg); color: var(--blue); }
.type-quiz   { background: var(--amber-bg); color: var(--amber); }
.section-card-title {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}
.lesson-body {
  padding: 28px 32px;
  font-size: 0.97rem;
}
.lesson-body h3 { color: var(--text-primary); }
.lesson-body p  { color: var(--text-secondary); }
.lesson-body ul, .lesson-body ol { color: var(--text-secondary); }

/* ── Code Blocks ── */
.code-block {
  background: #0d0d14;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin: 1.2em 0;
  overflow: hidden;
}
.code-label {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.07em;
  padding: 8px 16px;
  border-bottom: 1px solid var(--border);
  background: rgba(255,255,255,0.02);
}
.code-block pre {
  margin: 0;
  padding: 16px;
  overflow-x: auto;
}
.code-block code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.88rem;
  background: none;
  border: none;
  padding: 0;
  color: #c9d1d9;
  white-space: pre;
}

/* ── Callouts ── */
.callout {
  border-radius: var(--radius);
  padding: 14px 18px;
  margin: 1.2em 0;
  border-left: 3px solid;
  font-size: 0.93rem;
}
.callout p { margin: 0; }
.callout-info  { background: var(--blue-bg);  border-color: var(--blue);  color: #93c5fd; }
.callout-tip   { background: var(--green-bg); border-color: var(--green); color: #86efac; }
.callout-warn  { background: var(--amber-bg); border-color: var(--amber); color: #fcd34d; }
.callout strong { color: inherit; }

/* ── Comparison Table ── */
.comparison-table {
  overflow-x: auto;
  margin: 1.2em 0;
}
.comparison-table table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}
.comparison-table th {
  background: var(--bg-glass);
  color: var(--text-primary);
  padding: 10px 16px;
  text-align: left;
  font-weight: 600;
  border-bottom: 2px solid var(--border);
}
.comparison-table td {
  padding: 10px 16px;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border);
}
.comparison-table tr:last-child td { border-bottom: none; }
.comparison-table tr:hover td { background: var(--bg-glass); }

/* ── Git Stages Visual ── */
.stages {
  display: flex;
  align-items: center;
  gap: 0;
  margin: 1.2em 0;
  flex-wrap: wrap;
}
.stage {
  flex: 1;
  min-width: 120px;
  background: var(--bg-glass);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px;
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-secondary);
}
.stage .stage-num {
  display: block;
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--accent-light);
  margin-bottom: 6px;
}
.stage strong { color: var(--text-primary); display: block; margin-bottom: 4px; }
.stage-arrow { color: var(--text-muted); font-size: 1.5rem; padding: 0 8px; }

/* ── Quiz Engine ── */
.quiz-body { padding: 28px 32px; }
.quiz-progress {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
}
.quiz-progress-text {
  font-size: 0.82rem;
  color: var(--text-muted);
  font-weight: 500;
}
.quiz-progress-dots {
  display: flex;
  gap: 6px;
}
.q-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--border);
  transition: background var(--transition);
}
.q-dot.active   { background: var(--accent); }
.q-dot.correct  { background: var(--green); }
.q-dot.wrong    { background: var(--red); }
.quiz-question {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 24px;
  line-height: 1.5;
  white-space: pre-wrap;
}
.options-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 20px;
}
.option-btn {
  background: var(--bg-glass);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.9rem;
  text-align: left;
  cursor: pointer;
  transition: all var(--transition);
  line-height: 1.4;
  position: relative;
  overflow: hidden;
}
.option-btn:hover:not(:disabled) {
  background: var(--bg-glass-hover);
  border-color: var(--border-bright);
  color: var(--text-primary);
  transform: translateY(-1px);
}
.option-btn.correct {
  background: var(--green-bg);
  border-color: var(--green);
  color: var(--green);
  animation: popIn 0.25s ease;
}
.option-btn.wrong {
  background: var(--red-bg);
  border-color: var(--red);
  color: var(--red);
  animation: shakeIt 0.4s ease;
}
@keyframes popIn {
  0% { transform: scale(0.97); }
  50% { transform: scale(1.02); }
  100% { transform: scale(1); }
}
@keyframes shakeIt {
  0%, 100% { transform: translateX(0); }
  20%       { transform: translateX(-5px); }
  40%       { transform: translateX(5px); }
  60%       { transform: translateX(-4px); }
  80%       { transform: translateX(4px); }
}
.option-btn:disabled { cursor: default; }

.explanation-box {
  border-radius: var(--radius);
  padding: 14px 18px;
  margin-top: 4px;
  font-size: 0.9rem;
  animation: fadeUp 0.3s ease;
  display: none;
}
.explanation-box.show { display: block; }
.explanation-box.good { background: var(--green-bg); border-left: 3px solid var(--green); color: #86efac; }
.explanation-box.bad  { background: var(--red-bg);   border-left: 3px solid var(--red);   color: #fca5a5; }
.explanation-box strong { color: inherit; }

/* ── Quiz Score ── */
.quiz-score-screen {
  text-align: center;
  padding: 40px 32px;
  animation: fadeUp 0.4s ease;
}
.score-circle {
  width: 120px; height: 120px;
  border-radius: 50%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin: 0 auto 24px;
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  border: 3px solid;
}
.score-circle.excellent { border-color: var(--green);  background: var(--green-bg);  color: var(--green); }
.score-circle.good      { border-color: var(--amber);  background: var(--amber-bg);  color: var(--amber); }
.score-circle.poor      { border-color: var(--red);    background: var(--red-bg);    color: var(--red); }
.score-label { font-size: 0.65rem; font-weight: 700; letter-spacing: 0.1em; text-transform: uppercase; }
.score-message { font-size: 1.2rem; font-weight: 700; color: var(--text-primary); margin-bottom: 8px; }
.score-sub { font-size: 0.9rem; color: var(--text-muted); margin-bottom: 28px; }

/* ── Action Buttons ── */
.action-row {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  padding: 20px 32px 28px;
  border-top: 1px solid var(--border);
}
.btn {
  padding: 12px 24px;
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  border: 1px solid transparent;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-light));
  color: #fff;
  border-color: transparent;
}
.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 8px 25px var(--accent-glow);
}
.btn-secondary {
  background: var(--bg-glass);
  color: var(--text-secondary);
  border-color: var(--border);
}
.btn-secondary:hover {
  background: var(--bg-glass-hover);
  color: var(--text-primary);
  border-color: var(--border-bright);
}

/* ── Completion Screen ── */
.completion-screen {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 60px 40px;
  text-align: center;
  animation: fadeUp 0.5s ease;
}
.completion-icon { font-size: 4rem; margin-bottom: 20px; display: block; }
.completion-title {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 12px;
}
.completion-sub {
  color: var(--text-secondary);
  margin-bottom: 32px;
  max-width: 400px;
  margin-left: auto;
  margin-right: auto;
}
.completion-stats {
  display: flex;
  justify-content: center;
  gap: 32px;
  margin-bottom: 36px;
  flex-wrap: wrap;
}
.comp-stat { text-align: center; }
.comp-stat-val { font-size: 2rem; font-weight: 800; color: var(--accent-light); }
.comp-stat-lbl { font-size: 0.78rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.05em; }

/* ── Footer ── */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 32px 24px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}
.site-footer a { color: var(--accent-light); text-decoration: none; }

/* ── Responsive ── */
@media (max-width: 768px) {
  .reader-layout {
    grid-template-columns: 1fr;
  }
  .progress-sidebar {
    position: static;
    order: -1;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 16px;
  }
  .section-steps::before { display: none; }
  .section-steps { flex-direction: row; flex-wrap: wrap; gap: 8px; }
  .step-item { padding: 6px 12px 6px 28px; }
  .options-grid { grid-template-columns: 1fr; }
  .action-row { padding: 16px 20px 20px; }
  .lesson-body, .quiz-body { padding: 20px; }
  .section-card-header { padding: 20px 20px 16px; }
  .hero { padding: 48px 24px 40px; }
  .hero-stats { gap: 24px; }
  .topics-grid { grid-template-columns: 1fr; }
}