:root {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --bg-card: rgba(30, 41, 59, 0.85);
  --bg-card-hover: rgba(51, 65, 85, 0.9);
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent-cyan: #06b6d4;
  --accent-blue: #3b82f6;
  --accent-indigo: #6366f1;
  --accent-purple: #8b5cf6;
  --accent-emerald: #10b981;
  --accent-amber: #f59e0b;
  --accent-rose: #f43f5e;
  --border-color: #334155;
  --border-glow: rgba(59, 130, 246, 0.3);
  --code-bg: #090d16;
  --header-glass: rgba(15, 23, 42, 0.88);
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
  --shadow-glow: 0 0 25px rgba(6, 182, 212, 0.25);
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --font-main: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-code: 'Fira Code', 'JetBrains Mono', Consolas, Monaco, monospace;
}

[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9;
  --bg-card: rgba(255, 255, 255, 0.95);
  --bg-card-hover: #ffffff;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --border-color: #e2e8f0;
  --border-glow: rgba(59, 130, 246, 0.2);
  --code-bg: #1e293b;
  --header-glass: rgba(255, 255, 255, 0.9);
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 25px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-glow: 0 0 20px rgba(59, 130, 246, 0.15);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-main);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.65;
  transition: background-color 0.3s ease, color 0.3s ease;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg-primary);
}
::-webkit-scrollbar-thumb {
  background: var(--bg-tertiary);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--accent-blue);
}

/* Header & Nav */
header.app-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--header-glass);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  padding: 0.75rem 1.5rem;
}

.header-container {
  max-width: 1400px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--text-primary);
}

.brand-icon {
  width: 38px;
  height: 38px;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 800;
  font-size: 1.2rem;
  box-shadow: 0 0 15px rgba(6, 182, 212, 0.4);
}

.brand-title {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  background: linear-gradient(90deg, #38bdf8, #818cf8);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.brand-subtitle {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  list-style: none;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 0.9rem;
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all 0.2s ease;
}

.nav-link:hover, .nav-link.active {
  color: #fff;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
}

.nav-link.active {
  background: linear-gradient(135deg, rgba(6, 182, 212, 0.15), rgba(59, 130, 246, 0.15));
  color: var(--accent-cyan);
  border-color: var(--accent-cyan);
}

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

.btn-icon {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-icon:hover {
  color: var(--text-primary);
  border-color: var(--accent-blue);
  box-shadow: 0 0 10px rgba(59, 130, 246, 0.2);
}

/* Main Layout */
main.main-content {
  flex: 1;
  max-width: 1400px;
  width: 100%;
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

/* Hero Section */
.hero-card {
  background: linear-gradient(135deg, rgba(15, 23, 42, 0.95), rgba(30, 41, 59, 0.9)), radial-gradient(circle at 10% 20%, rgba(6, 182, 212, 0.15) 0%, transparent 40%);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-lg), var(--shadow-glow);
  position: relative;
  overflow: hidden;
}

[data-theme="light"] .hero-card {
  background: linear-gradient(135deg, #ffffff, #f1f5f9), radial-gradient(circle at 10% 20%, rgba(6, 182, 212, 0.1) 0%, transparent 40%);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: rgba(6, 182, 212, 0.15);
  color: var(--accent-cyan);
  border: 1px solid rgba(6, 182, 212, 0.3);
  padding: 0.3rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: 1rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.hero-title {
  font-size: 2.2rem;
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 1rem;
  letter-spacing: -0.03em;
}

.hero-title span {
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue), var(--accent-purple));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-desc {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 850px;
  margin-bottom: 1.75rem;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1.25rem;
  margin-top: 1.5rem;
}

.stat-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.stat-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
}

.stat-val {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--text-primary);
}

.stat-lbl {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
}

/* Modules Grid */
.modules-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
  gap: 1.75rem;
  margin-bottom: 2.5rem;
}

.module-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  backdrop-filter: blur(10px);
}

.module-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent-blue);
  box-shadow: var(--shadow-lg), 0 0 20px rgba(59, 130, 246, 0.2);
}

.module-header {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.module-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.7rem;
  flex-shrink: 0;
}

.module-title {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 0.3rem;
  color: var(--text-primary);
}

.module-tag {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent-cyan);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.module-desc {
  color: var(--text-secondary);
  font-size: 0.92rem;
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.module-features {
  list-style: none;
  margin-bottom: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.module-features li {
  font-size: 0.85rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.module-features li::before {
  content: "✓";
  color: var(--accent-emerald);
  font-weight: bold;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  color: #fff;
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius-sm);
  font-size: 0.92rem;
  font-weight: 600;
  text-decoration: none;
  border: none;
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: 0 4px 12px rgba(6, 182, 212, 0.3);
}

.btn-primary:hover {
  opacity: 0.95;
  transform: translateY(-1px);
  box-shadow: 0 6px 18px rgba(6, 182, 212, 0.45);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  background: var(--bg-tertiary);
  color: var(--text-primary);
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius-sm);
  font-size: 0.92rem;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid var(--border-color);
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-secondary:hover {
  background: var(--bg-secondary);
  border-color: var(--accent-blue);
}

/* Search and Filter Bar */
.search-container {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-sm);
}

.search-input-wrapper {
  position: relative;
  flex: 1;
}

.search-input {
  width: 100%;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.65rem 1rem 0.65rem 2.5rem;
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.92rem;
  outline: none;
  transition: border-color 0.2s;
}

.search-input:focus {
  border-color: var(--accent-cyan);
  box-shadow: 0 0 0 2px rgba(6, 182, 212, 0.2);
}

.search-icon {
  position: absolute;
  left: 0.85rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

.filter-pills {
  display: flex;
  gap: 0.5rem;
  overflow-x: auto;
  padding-bottom: 2px;
}

.pill {
  padding: 0.4rem 0.8rem;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: 9999px;
  color: var(--text-secondary);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.2s;
}

.pill.active, .pill:hover {
  background: var(--accent-blue);
  color: #fff;
  border-color: var(--accent-blue);
}

/* Topic / Content Accordions & Cards */
.topic-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 1.5rem;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.topic-card:hover {
  border-color: rgba(59, 130, 246, 0.5);
}

.topic-header {
  padding: 1.25rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  background: var(--bg-secondary);
  border-bottom: 1px solid transparent;
  user-select: none;
  transition: background-color 0.2s;
}

.topic-header:hover {
  background: var(--bg-tertiary);
}

.topic-header.open {
  border-bottom-color: var(--border-color);
  background: var(--bg-secondary);
}

.topic-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.topic-badge {
  background: linear-gradient(135deg, var(--accent-indigo), var(--accent-purple));
  color: #fff;
  font-size: 0.82rem;
  font-weight: 700;
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-sm);
  min-width: 42px;
  text-align: center;
}

.topic-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
}

.topic-toggle-icon {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--bg-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  color: var(--text-secondary);
  transition: transform 0.3s ease;
}

.topic-header.open .topic-toggle-icon {
  transform: rotate(180deg);
  color: var(--accent-cyan);
}

.topic-body {
  padding: 1.75rem 2rem;
  display: none;
}

.topic-body.open {
  display: block;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Rich Content Typography */
.content-section {
  margin-bottom: 1.75rem;
}

.content-section h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--accent-cyan);
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.content-section h4 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--accent-amber);
  margin: 1rem 0 0.5rem 0;
}

.content-section p {
  color: var(--text-secondary);
  margin-bottom: 0.85rem;
  font-size: 0.95rem;
}

.content-section ul, .content-section ol {
  margin-left: 1.5rem;
  margin-bottom: 1rem;
  color: var(--text-secondary);
  font-size: 0.93rem;
}

.content-section li {
  margin-bottom: 0.35rem;
}

.formula-box {
  background: var(--code-bg);
  border: 1px solid var(--border-color);
  border-left: 3px solid var(--accent-cyan);
  border-radius: var(--radius-sm);
  padding: 0.65rem 1.1rem;
  margin: 0.75rem 0;
  font-family: var(--font-code);
  font-size: 0.88rem;
  color: #38bdf8;
  display: inline-block;
  max-width: 100%;
  overflow-x: auto;
}

/* Callout / Alert boxes */
.callout {
  border-radius: var(--radius-sm);
  padding: 1rem 1.25rem;
  margin: 1.25rem 0;
  display: flex;
  gap: 0.85rem;
  font-size: 0.9rem;
}

.callout-info {
  background: rgba(6, 182, 212, 0.1);
  border-left: 4px solid var(--accent-cyan);
  color: var(--text-primary);
}

.callout-warning {
  background: rgba(245, 158, 11, 0.1);
  border-left: 4px solid var(--accent-amber);
  color: var(--text-primary);
}

.callout-tip {
  background: rgba(16, 185, 129, 0.1);
  border-left: 4px solid var(--accent-emerald);
  color: var(--text-primary);
}

.callout-danger {
  background: rgba(244, 63, 94, 0.1);
  border-left: 4px solid var(--accent-rose);
  color: var(--text-primary);
}

.callout-icon {
  font-size: 1.25rem;
  flex-shrink: 0;
}

/* Tables */
.table-responsive {
  overflow-x: auto;
  margin: 1.25rem 0;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

table.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  text-align: left;
}

table.data-table th {
  background: var(--bg-secondary);
  color: var(--accent-cyan);
  padding: 0.75rem 1rem;
  font-weight: 700;
  border-bottom: 1px solid var(--border-color);
  white-space: nowrap;
}

table.data-table td {
  padding: 0.65rem 1rem;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-secondary);
}

table.data-table tr:last-child td {
  border-bottom: none;
}

table.data-table tr:hover td {
  background: rgba(59, 130, 246, 0.05);
  color: var(--text-primary);
}

/* Code Snippets */
.code-block-wrapper {
  background: var(--code-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  margin: 1.25rem 0;
  overflow: hidden;
}

.code-header {
  background: rgba(255, 255, 255, 0.04);
  padding: 0.5rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-color);
  font-family: var(--font-code);
  font-size: 0.78rem;
  color: var(--text-muted);
}

.code-lang-badge {
  color: var(--accent-cyan);
  font-weight: 600;
  text-transform: uppercase;
}

.btn-copy {
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 0.78rem;
  display: flex;
  align-items: center;
  gap: 0.35rem;
  transition: color 0.2s;
}

.btn-copy:hover {
  color: var(--text-primary);
}

pre.code-block {
  padding: 1.25rem 1rem;
  overflow-x: auto;
  font-family: var(--font-code);
  font-size: 0.86rem;
  line-height: 1.55;
  color: #e2e8f0;
}

/* Quiz UI Components */
.quiz-container {
  max-width: 900px;
  margin: 0 auto;
}

.quiz-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-md);
  transition: all 0.2s ease;
}

.quiz-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
}

.quiz-badge {
  background: rgba(99, 102, 241, 0.15);
  color: var(--accent-indigo);
  border: 1px solid rgba(99, 102, 241, 0.3);
  padding: 0.25rem 0.65rem;
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 700;
}

.quiz-question-text {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  line-height: 1.45;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
}

.quiz-option {
  display: flex;
  align-items: center;
  gap: 1rem;
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.9rem 1.1rem;
  cursor: pointer;
  transition: all 0.2s ease;
  user-select: none;
  font-size: 0.92rem;
  color: var(--text-secondary);
}

.quiz-option:hover:not(.locked) {
  border-color: var(--accent-blue);
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.quiz-option-letter {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--bg-tertiary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.82rem;
  flex-shrink: 0;
  color: var(--text-primary);
}

.quiz-option.correct {
  border-color: var(--accent-emerald) !important;
  background: rgba(16, 185, 129, 0.12) !important;
  color: #fff !important;
}

.quiz-option.correct .quiz-option-letter {
  background: var(--accent-emerald) !important;
  color: #fff !important;
}

.quiz-option.incorrect {
  border-color: var(--accent-rose) !important;
  background: rgba(244, 63, 94, 0.12) !important;
  color: #fff !important;
}

.quiz-option.incorrect .quiz-option-letter {
  background: var(--accent-rose) !important;
  color: #fff !important;
}

.quiz-explanation {
  background: var(--bg-secondary);
  border-radius: var(--radius-sm);
  padding: 1.25rem;
  border-left: 4px solid var(--accent-blue);
  margin-top: 1rem;
  display: none;
  animation: fadeIn 0.3s ease;
}

.quiz-explanation.show {
  display: block;
}

.quiz-explanation-title {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--accent-cyan);
  margin-bottom: 0.4rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.quiz-explanation-text {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Score Banner */
.score-banner {
  background: linear-gradient(135deg, var(--bg-card), var(--bg-secondary));
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  text-align: center;
  margin-bottom: 2.5rem;
  box-shadow: var(--shadow-lg);
}

.score-number {
  font-size: 3rem;
  font-weight: 900;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-emerald));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 0.5rem;
}

.progress-bar-container {
  width: 100%;
  height: 10px;
  background: var(--bg-primary);
  border-radius: 9999px;
  overflow: hidden;
  margin: 1.5rem 0;
}

.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-blue), var(--accent-emerald));
  width: 0%;
  transition: width 0.4s ease;
}

/* Footer */
footer.app-footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 2rem 1.5rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
  margin-top: auto;
}

footer a {
  color: var(--accent-cyan);
  text-decoration: none;
}

/* Responsive */
@media (max-width: 768px) {
  .header-container {
    flex-wrap: wrap;
  }
  .nav-links {
    order: 3;
    width: 100%;
    justify-content: center;
    padding-top: 0.5rem;
  }
  .hero-card {
    padding: 1.5rem;
  }
  .hero-title {
    font-size: 1.6rem;
  }
  .topic-body {
    padding: 1.25rem 1rem;
  }
  .modules-grid {
    grid-template-columns: 1fr;
  }
}