/* ============================================
   PE Chemistry Exam Study Site
   Design System — #006938 green base, clean & simple
   ============================================ */

/* --- CSS Custom Properties --- */
:root {
  /* Primary palette based on #006938 */
  --color-primary: #006938;
  --color-primary-light: #00875a;
  --color-primary-dark: #004d2a;
  --color-primary-bg: #e8f5ee;
  --color-primary-bg-hover: #d1eadd;

  /* Subject colors */
  --color-inorganic: #2563eb;
  --color-inorganic-bg: #eff6ff;
  --color-organic: #059669;
  --color-organic-bg: #ecfdf5;
  --color-polymer: #d97706;
  --color-polymer-bg: #fffbeb;
  --color-process: #dc2626;
  --color-process-bg: #fef2f2;

  /* Neutral palette */
  --color-bg: #ffffff;
  --color-bg-secondary: #f8fafb;
  --color-bg-tertiary: #f1f5f9;
  --color-surface: #ffffff;
  --color-border: #e2e8f0;
  --color-border-light: #f1f5f9;
  --color-text: #1e293b;
  --color-text-secondary: #64748b;
  --color-text-muted: #94a3b8;

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;

  /* Typography */
  --font-sans: 'Noto Sans JP', 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);

  /* Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  /* Container */
  --container-max: 860px;
  --container-wide: 1100px;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: var(--color-primary-light);
}

img {
  max-width: 100%;
  height: auto;
}

/* --- Layout --- */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.container-wide {
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* ============================================
   HEADER
   ============================================ */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.header-inner {
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.header-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-weight: 700;
  font-size: 1rem;
  color: var(--color-primary);
  text-decoration: none;
}

.header-logo-icon {
  width: 28px;
  height: 28px;
  background: var(--color-primary);
  color: white;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 800;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
}

.header-nav a {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  font-weight: 500;
  transition: color 0.2s;
}

.header-nav a:hover {
  color: var(--color-primary);
}

/* Mobile menu */
.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  width: 24px;
  height: 20px;
  flex-direction: column;
  justify-content: space-between;
}

.mobile-menu-btn span {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}

/* ============================================
   HERO (Top page)
   ============================================ */
.hero {
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-3xl) 0;
  text-align: center;
}

.hero-label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-primary);
  background: var(--color-primary-bg);
  padding: var(--space-xs) var(--space-md);
  border-radius: 100px;
  margin-bottom: var(--space-md);
  letter-spacing: 0.05em;
}

.hero h1 {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--color-text);
  line-height: 1.4;
  margin-bottom: var(--space-md);
}

.hero-description {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  max-width: 560px;
  margin: 0 auto;
  line-height: 1.8;
}

/* ============================================
   SECTION COMMON
   ============================================ */
.section {
  padding: var(--space-3xl) 0;
}

.section-label {
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: var(--space-sm);
}

.section-heading {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-xl);
}

/* ============================================
   YEAR CARDS (Top page)
   ============================================ */
.year-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: var(--space-md);
}

.year-card {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-lg);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: border-color 0.2s, box-shadow 0.2s, transform 0.15s;
}

.year-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
  color: var(--color-text);
}

.year-card-year {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-primary);
}

.year-card-label {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
}

.year-card-count {
  font-size: 0.7rem;
  color: var(--color-text-muted);
  margin-top: 2px;
}

/* ============================================
   SEARCH
   ============================================ */
.search-section {
  padding: var(--space-2xl) 0;
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.search-box {
  position: relative;
  max-width: 600px;
  margin: 0 auto;
}

.search-input {
  width: 100%;
  padding: var(--space-md) var(--space-lg);
  font-size: 0.95rem;
  font-family: var(--font-sans);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
  color: var(--color-text);
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.search-input::placeholder {
  color: var(--color-text-muted);
}

.search-input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-bg);
}

.search-results {
  margin-top: var(--space-md);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.search-result-item {
  display: block;
  padding: var(--space-md) var(--space-lg);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-sm);
  text-decoration: none;
  transition: border-color 0.2s;
}

.search-result-item:hover {
  border-color: var(--color-primary);
  color: var(--color-text);
}

.search-result-title {
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--color-text);
}

.search-result-excerpt {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  margin-top: 2px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.search-result-tag {
  display: inline-block;
  font-size: 0.65rem;
  padding: 1px 8px;
  border-radius: 100px;
  font-weight: 600;
  margin-right: 6px;
}

.search-no-results {
  text-align: center;
  padding: var(--space-lg);
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* ============================================
   NOTE PROMOTION CARD
   ============================================ */
.note-promo {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  padding: var(--space-lg) var(--space-xl);
  background: var(--color-primary-bg);
  border: 1px solid rgba(0, 105, 56, 0.15);
  border-radius: var(--radius-lg);
  text-decoration: none;
  transition: box-shadow 0.2s, transform 0.15s;
  color: var(--color-text);
}

.note-promo:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
  color: var(--color-text);
}

.note-promo-content h3 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin-bottom: 4px;
}

.note-promo-content p {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.note-promo-arrow {
  margin-left: auto;
  font-size: 1.2rem;
  color: var(--color-primary);
  flex-shrink: 0;
}

/* Small variant for year/question pages */
.note-promo-sm {
  padding: var(--space-md) var(--space-lg);
  gap: var(--space-md);
}

.note-promo-sm .note-promo-content h3 {
  font-size: 0.85rem;
}

.note-promo-sm .note-promo-content p {
  font-size: 0.75rem;
}

/* ============================================
   CHANGELOG
   ============================================ */
.changelog-list {
  list-style: none;
}

.changelog-item {
  display: flex;
  gap: var(--space-md);
  padding: var(--space-sm) 0;
  font-size: 0.85rem;
  border-bottom: 1px solid var(--color-border-light);
}

.changelog-item:last-child {
  border-bottom: none;
}

.changelog-date {
  color: var(--color-text-muted);
  font-variant-numeric: tabular-nums;
  flex-shrink: 0;
  font-size: 0.8rem;
}

.changelog-text {
  color: var(--color-text-secondary);
}

/* ============================================
   BREADCRUMB
   ============================================ */
.breadcrumb {
  padding: var(--space-md) 0;
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

.breadcrumb a {
  color: var(--color-text-muted);
}

.breadcrumb a:hover {
  color: var(--color-primary);
}

.breadcrumb-sep {
  margin: 0 var(--space-sm);
  color: var(--color-border);
}

/* ============================================
   YEAR PAGE — Question List
   ============================================ */
.year-hero {
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-2xl) 0 var(--space-xl);
}

.year-hero h1 {
  font-size: 1.5rem;
  font-weight: 700;
}

.year-hero-sub {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-top: var(--space-xs);
}

/* Subject filter */
.subject-filter {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-bottom: var(--space-xl);
}

.subject-filter-btn {
  font-family: var(--font-sans);
  font-size: 0.75rem;
  font-weight: 600;
  padding: var(--space-xs) var(--space-md);
  border-radius: 100px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all 0.2s;
}

.subject-filter-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.subject-filter-btn.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: white;
}

.subject-filter-btn[data-subject="all"].active {
  background: var(--color-primary);
  border-color: var(--color-primary);
}

.subject-filter-btn[data-subject="無機化学及びセラミックス"].active {
  background: var(--color-inorganic);
  border-color: var(--color-inorganic);
}

.subject-filter-btn[data-subject="有機化学及び燃料"].active {
  background: var(--color-organic);
  border-color: var(--color-organic);
}

.subject-filter-btn[data-subject="高分子化学"].active {
  background: var(--color-polymer);
  border-color: var(--color-polymer);
}

.subject-filter-btn[data-subject="化学プロセス"].active {
  background: var(--color-process);
  border-color: var(--color-process);
}

/* Question list cards */
.question-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.question-card {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md) var(--space-lg);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: border-color 0.2s, box-shadow 0.2s;
  color: var(--color-text);
}

.question-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-sm);
  color: var(--color-text);
}

.question-card-num {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--color-primary);
  min-width: 40px;
}

.question-card-text {
  flex: 1;
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* Subject tag */
.subject-tag {
  display: inline-block;
  font-size: 0.65rem;
  font-weight: 600;
  padding: 2px 10px;
  border-radius: 100px;
  white-space: nowrap;
}

.subject-tag[data-subject="無機化学及びセラミックス"] {
  background: var(--color-inorganic-bg);
  color: var(--color-inorganic);
}

.subject-tag[data-subject="有機化学及び燃料"] {
  background: var(--color-organic-bg);
  color: var(--color-organic);
}

.subject-tag[data-subject="高分子化学"] {
  background: var(--color-polymer-bg);
  color: var(--color-polymer);
}

.subject-tag[data-subject="化学プロセス"] {
  background: var(--color-process-bg);
  color: var(--color-process);
}

.question-card-arrow {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* ============================================
   QUESTION PAGE
   ============================================ */
.question-hero {
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-xl) 0;
}

.question-hero h1 {
  font-size: 1.35rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: var(--space-md);
  flex-wrap: wrap;
}

/* Question body card */
.question-body {
  margin: var(--space-xl) 0;
}

.question-text-card {
  padding: var(--space-xl);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  font-size: 0.95rem;
  line-height: 2;
  white-space: pre-wrap;
}

/* Choices */
.choices {
  margin-top: var(--space-lg);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.choices.choices-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-lg);
}

@media (max-width: 600px) {
  .choices.choices-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.choice-wrapper {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.image-choice-wrapper {
  position: relative;
  display: block;
}

.image-choice-num {
  position: absolute;
  top: 8px;
  left: 12px;
  z-index: 10;
  font-size: 1.1rem;
  font-weight: bold;
  color: var(--color-text);
  pointer-events: none;
}

.choice-item {
  flex: 1;
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
  padding: var(--space-md) var(--space-lg);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  line-height: 1.7;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s, box-shadow 0.2s;
  user-select: none;
}

.choice-item.choice-is-image {
  padding: var(--space-md);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
}

.choice-image {
  max-width: 100%;
  height: auto;
  display: block;
  mix-blend-mode: multiply;
}

.choice-eliminate-btn.eliminate-top-right {
  position: absolute;
  top: -12px;
  right: -12px;
  z-index: 10;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  font-size: 1.2rem;
  box-shadow: var(--shadow-sm);
}

.choice-eliminate-btn {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  font-size: 1.5rem;
  color: var(--color-text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  transition: all 0.2s;
  padding: 0;
}

.choice-eliminate-btn:hover {
  border-color: #ef4444;
  color: #ef4444;
  background: #fef2f2;
}

.choice-wrapper.eliminated .choice-item {
  opacity: 0.5;
  background: var(--color-bg-tertiary);
  border-color: var(--color-border);
}

.choice-wrapper.eliminated .choice-text {
  text-decoration: line-through;
}

.choice-wrapper.eliminated .choice-eliminate-btn {
  color: #ef4444;
  border-color: #ef4444;
  background: #fef2f2;
}

.choice-wrapper.answered-global .choice-eliminate-btn {
  opacity: 0;
  pointer-events: none;
}

.choice-item:hover:not(.answered) {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

.choice-item.correct {
  border-color: var(--color-primary);
  background: var(--color-primary-bg);
  cursor: default;
}

.choice-item.incorrect-selected {
  border-color: #ef4444;
  background: #fef2f2;
  cursor: default;
}

.choice-item.selected {
  box-shadow: 0 0 0 2px var(--color-primary);
}

.choice-item.incorrect-selected.selected {
  box-shadow: 0 0 0 2px #ef4444;
}

.choice-item.answered {
  cursor: default;
  opacity: 0.5;
  background: var(--color-bg-tertiary);
  border-color: var(--color-border);
}

.choice-item.answered.correct,
.choice-item.answered.incorrect-selected {
  opacity: 1;
}

.choice-num {
  font-weight: 700;
  color: var(--color-primary);
  flex-shrink: 0;
  min-width: 24px;
}

.choice-text {
  color: var(--color-text);
}

/* Answer & explanation section */
.answer-section {
  margin-top: var(--space-xl);
}

.answer-content {
  display: none;
  margin-top: var(--space-md);
  animation: slideDown 0.3s ease;
}

.answer-content.visible {
  display: block;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-8px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.answer-box {
  padding: var(--space-lg) var(--space-xl);
  background: var(--color-primary-bg);
  border-radius: var(--radius-md);
  border-left: 4px solid var(--color-primary);
}

.answer-label {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: 0.05em;
  margin-bottom: var(--space-xs);
}

.answer-value {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-primary-dark);
}

/* Explanation */
.explanation-section {
  margin-top: var(--space-lg);
}

.explanation-content {
  padding: var(--space-xl);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  line-height: 2;
  white-space: pre-wrap;
}

/* Article links grid */
.article-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.article-link-card {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md) var(--space-lg);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: border-color 0.2s, box-shadow 0.2s;
  color: var(--color-text);
}

.article-link-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-sm);
  color: var(--color-text);
}

.article-link-card-text h4 {
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 2px;
}

.article-link-card-text p {
  font-size: 0.75rem;
  color: var(--color-text-secondary);
}

/* References */
.references-section {
  margin-top: var(--space-xl);
}

.reference-details {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.reference-summary {
  padding: var(--space-md) var(--space-lg);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  background: var(--color-bg-secondary);
  transition: background 0.2s;
  list-style: none;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.reference-summary::-webkit-details-marker {
  display: none;
}

.reference-summary:hover {
  background: var(--color-border);
}

.reference-summary::before {
  content: "▶";
  font-size: 0.8rem;
  color: var(--color-text-muted);
  transition: transform 0.2s;
}

.reference-details[open] .reference-summary::before {
  transform: rotate(90deg);
}

.reference-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg);
}

.reference-link {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: var(--space-md) var(--space-lg);
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-decoration: none;
  font-size: 0.85rem;
  color: var(--color-text);
  transition: border-color 0.2s;
}

.reference-link:hover {
  border-color: var(--color-primary);
  color: var(--color-text);
}

.reference-link-title {
  font-weight: 500;
  line-height: 1.5;
}

.reference-link-url {
  font-size: 0.7rem;
  color: var(--color-text-muted);
  word-break: break-all;
  line-height: 1.4;
}

/* Question navigation */
.question-nav {
  display: flex;
  justify-content: space-between;
  gap: var(--space-md);
  margin-top: var(--space-3xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border);
}

.question-nav-btn {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-text);
  transition: border-color 0.2s, box-shadow 0.2s;
}

.question-nav-btn:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-sm);
  color: var(--color-text);
}

.question-nav-btn.disabled {
  opacity: 0.4;
  pointer-events: none;
}

.question-nav-label {
  font-size: 0.7rem;
  color: var(--color-text-muted);
  font-weight: 400;
}

/* Year navigation (bottom of year page) */
.year-nav {
  display: flex;
  justify-content: space-between;
  gap: var(--space-md);
  margin-top: var(--space-2xl);
  padding-top: var(--space-xl);
  border-top: 1px solid var(--color-border);
}

/* ============================================
   FOOTER
   ============================================ */
.footer {
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  padding: var(--space-xl) 0;
  margin-top: auto;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-md);
}

.footer-left {
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

.footer-links {
  display: flex;
  gap: var(--space-lg);
}

.footer-links a {
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

.footer-links a:hover {
  color: var(--color-primary);
}

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 768px) {
  .header-nav {
    display: none;
    position: fixed;
    top: 56px;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(12px);
    flex-direction: column;
    padding: var(--space-lg);
    border-bottom: 1px solid var(--color-border);
    gap: var(--space-md);
  }

  .header-nav.open {
    display: flex;
  }

  .mobile-menu-btn {
    display: flex;
  }

  .hero h1 {
    font-size: 1.35rem;
  }

  .year-grid {
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: var(--space-sm);
  }

  .year-card {
    padding: var(--space-md);
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-xs);
  }

  .question-hero h1 {
    font-size: 1.15rem;
  }

  .question-text-card {
    padding: var(--space-lg);
  }

  .question-nav {
    flex-direction: column;
  }

  .question-nav-btn {
    justify-content: center;
  }

  .note-promo {
    flex-direction: column;
    text-align: center;
    padding: var(--space-lg);
  }

  .note-promo-arrow {
    display: none;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {

  .container,
  .container-wide {
    padding: 0 var(--space-md);
  }

  .hero {
    padding: var(--space-2xl) 0;
  }

  .hero h1 {
    font-size: 1.2rem;
  }

  .section {
    padding: var(--space-2xl) 0;
  }

  .section-heading {
    font-size: 1.15rem;
  }
}

/* ============================================
   ARTICLE PAGE
   ============================================ */
.article-hero {
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-2xl) 0 var(--space-xl);
}

.article-hero h1 {
  font-size: 1.5rem;
  font-weight: 700;
  line-height: 1.6;
}

.article-hero-meta {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-top: var(--space-sm);
}

.article-body {
  padding: var(--space-2xl) 0 var(--space-3xl);
}

.article-body h2 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-text);
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--color-primary);
}

.article-body h3 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-text);
  margin-top: var(--space-xl);
  margin-bottom: var(--space-md);
  padding-left: var(--space-md);
  border-left: 3px solid var(--color-primary-light);
}

.article-body p {
  font-size: 0.95rem;
  line-height: 2;
  color: var(--color-text);
  margin-bottom: var(--space-md);
}

.article-body .article-table-wrapper {
  overflow-x: auto;
  margin: var(--space-lg) 0;
  -webkit-overflow-scrolling: touch;
}

.article-body .article-chart-wrapper {
  margin: var(--space-lg) 0 var(--space-2xl);
  padding: var(--space-lg);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}

.article-body table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
  line-height: 1.7;
}

.article-body thead th {
  background: var(--color-primary);
  color: #fff;
  font-weight: 600;
  padding: var(--space-sm) var(--space-md);
  text-align: left;
  white-space: nowrap;
}

.article-body tbody td {
  padding: var(--space-sm) var(--space-md);
  border-bottom: 1px solid var(--color-border);
  vertical-align: top;
}

.article-body tbody tr:nth-child(even) {
  background: var(--color-bg-secondary);
}

.article-body tbody tr:hover {
  background: var(--color-primary-bg);
}

.article-body blockquote {
  margin: var(--space-lg) 0;
  padding: var(--space-md) var(--space-xl);
  background: var(--color-bg-secondary);
  border-left: 4px solid var(--color-primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  line-height: 1.8;
}

.article-body blockquote cite {
  display: block;
  margin-top: var(--space-sm);
  font-size: 0.75rem;
  color: var(--color-text-muted);
  font-style: normal;
}

.article-body .article-source {
  margin-top: var(--space-2xl);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-border);
}

.article-body .article-source h2 {
  font-size: 1rem;
  margin-top: 0;
}

.article-body .article-source ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.article-body .article-source li a {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  word-break: break-all;
}

.article-body .article-source li a:hover {
  color: var(--color-primary);
}

@media (max-width: 768px) {
  .article-hero h1 {
    font-size: 1.2rem;
  }

  .article-body table {
    font-size: 0.75rem;
  }

  .article-body thead th,
  .article-body tbody td {
    padding: var(--space-xs) var(--space-sm);
  }
}