/* dojo-site shared stylesheet
   v2: light/dark mode / typography / code-actions / pitfalls / manual-ref */

:root {
  /* Light theme (default) */
  --color-bg: #fdfdfd;
  --color-surface: #ffffff;
  --color-surface-alt: #f8fafc;
  --color-text: #1f2937;
  --color-text-strong: #0f172a;
  --color-muted: #64748b;
  --color-primary: #1e3a8a;
  --color-primary-hover: #1e40af;
  --color-primary-light: #3b82f6;
  --color-accent: #f59e0b;
  --color-accent-hover: #d97706;
  --color-warn-bg: #fef3c7;
  --color-warn-border: #f59e0b;
  --color-info-bg: #dbeafe;
  --color-info-border: #3b82f6;
  --color-border: #e5e7eb;
  --color-border-strong: #cbd5e1;
  --color-code-bg: #f3f4f6;
  --color-code-block-bg: #0d1117;
  --color-code-block-fg: #c9d1d9;

  --max-width: 960px;
  --max-width-prose: 760px;
  --radius: 10px;
  --radius-sm: 6px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN", "Noto Sans JP", "Yu Gothic UI", sans-serif;
  --font-mono: ui-monospace, "SF Mono", "JetBrains Mono", "Cascadia Code", Menlo, Consolas, monospace;

  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --color-bg: #0f172a;
    --color-surface: #1e293b;
    --color-surface-alt: #0b1220;
    --color-text: #e2e8f0;
    --color-text-strong: #f1f5f9;
    --color-muted: #94a3b8;
    --color-primary: #60a5fa;
    --color-primary-hover: #93c5fd;
    --color-primary-light: #93c5fd;
    --color-accent: #fbbf24;
    --color-accent-hover: #f59e0b;
    --color-warn-bg: #422006;
    --color-warn-border: #f59e0b;
    --color-info-bg: #172554;
    --color-info-border: #3b82f6;
    --color-border: #334155;
    --color-border-strong: #475569;
    --color-code-bg: #0b1220;
    --color-code-block-bg: #020617;
    --color-code-block-fg: #cbd5e1;
    color-scheme: dark;
  }
}

/* Reset */
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.8;
  font-feature-settings: "palt" 1;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
a { color: var(--color-primary); text-decoration: none; transition: color .15s; }
a:hover { color: var(--color-primary-hover); text-decoration: underline; }

.container { max-width: var(--max-width); margin: 0 auto; padding: 0 1.25rem; }
.icon { display: inline-block; vertical-align: -0.125em; width: 1em; height: 1em; }

/* Header */
.site-header {
  background: var(--color-primary);
  color: #fff;
  padding: 1rem 0;
  box-shadow: var(--shadow-sm);
  position: sticky; top: 0; z-index: 50;
}
.site-header .container { display: flex; align-items: center; justify-content: space-between; gap: 1rem; flex-wrap: wrap; }
.site-header .brand { color: #fff; font-weight: 700; font-size: 1.25rem; letter-spacing: 0.02em; }
.site-header nav { display: flex; gap: 1.25rem; }
.site-header nav a { color: #fff; opacity: 0.9; }
.site-header nav a:hover { opacity: 1; text-decoration: none; }

/* Footer */
.site-footer {
  background: var(--color-surface-alt);
  border-top: 1px solid var(--color-border);
  color: var(--color-muted);
  padding: 2.5rem 0 3rem;
  margin-top: 5rem;
  font-size: 0.875rem;
  line-height: 1.7;
}
.site-footer a { color: var(--color-primary); }
.site-footer .footer-nav { margin-top: 1rem; }
.site-footer .footer-nav a { margin-right: 1rem; }
.site-footer .footer-copyright { margin-top: 1rem; color: var(--color-muted); }

/* Hero */
.hero {
  text-align: center;
  padding: 4rem 0 3rem;
  border-bottom: 1px solid var(--color-border);
}
.hero h1 { font-size: clamp(2rem, 5vw, 3rem); margin: 0 0 .75rem; color: var(--color-primary); font-weight: 800; letter-spacing: -0.01em; }
.hero .tagline { font-size: 1.125rem; color: var(--color-muted); max-width: 600px; margin: 0 auto; }
.hero-actions { margin-top: 2rem; display: flex; justify-content: center; gap: .75rem; flex-wrap: wrap; }
.hero-stats {
  list-style: none;
  padding: 0;
  margin: 1.5rem 0 0;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem 2rem;
}
.hero-stats li { display: flex; flex-direction: column; align-items: center; }
.hero-stats .num { font-size: 1.875rem; font-weight: 800; color: var(--color-primary); line-height: 1; }
.hero-stats .lbl { font-size: .8125rem; color: var(--color-muted); margin-top: .25rem; }

/* Chapter list (lesson page) */
.chapters { margin: 2rem 0; }
.chapter-list { list-style: none; counter-reset: chapter; padding: 0; }
.chapter-list li { counter-increment: chapter; border-bottom: 1px solid var(--color-border); }
.chapter-list li:last-child { border-bottom: none; }
.chapter-list a {
  display: flex; align-items: center; gap: 1rem;
  padding: .875rem .5rem;
  color: var(--color-text);
  transition: background .15s;
}
.chapter-list a:hover { background: var(--color-surface-alt); text-decoration: none; }
.chapter-list .ch-num { font-family: var(--font-mono); font-weight: 700; color: var(--color-primary); min-width: 3.5rem; }
.chapter-list .ch-title { flex: 1; }
.chapter-list a::after { content: '→'; color: var(--color-muted); }

/* Drill list (chapter page) */
.drills { margin: 2rem 0; padding: 1.25rem 1.5rem; background: var(--color-surface-alt); border-radius: var(--radius); }
.drills h2 { margin: 0 0 1rem; font-size: 1.25rem; display: flex; align-items: center; gap: .5rem; color: var(--color-text-strong); border: none; padding: 0; }
.drill-list { list-style: none; counter-reset: drill; padding: 0; margin: 0; }
.drill-item { counter-increment: drill; padding: .75rem 0; border-bottom: 1px dashed var(--color-border-strong); }
.drill-item:last-child { border-bottom: none; }
.drill-item h3 { margin: 0; font-size: 1rem; color: var(--color-text-strong); }
.drill-item h3::before { content: counter(drill) ". "; color: var(--color-primary); font-weight: 700; }
.drill-meta { margin: .25rem 0 0; font-size: .8125rem; }
.badge { display: inline-block; padding: .125rem .5rem; background: var(--color-info-bg); color: var(--color-primary); border-radius: 999px; font-family: var(--font-mono); font-size: .75rem; margin-right: .375rem; }
.badge-answer { background: #dcfce7; color: #166534; }
.drill-note { margin: 1rem 0 0; font-size: .875rem; color: var(--color-muted); }

/* Chapter context (sub-heading above h1) */
.ch-context { color: var(--color-muted); font-size: .875rem; margin: 0 0 .25rem; }
.ch-context .ch-num { font-family: var(--font-mono); }

/* Operator info (dl on Contact page) */
.operator-info { display: grid; grid-template-columns: max-content 1fr; gap: .5rem 1.5rem; margin: 1rem 0; }
.operator-info dt { font-weight: 700; color: var(--color-text-strong); }
.operator-info dd { margin: 0; color: var(--color-text); }
.operator-info dd ul { margin: 0; padding-left: 1.25rem; }
@media (max-width: 640px) { .operator-info { grid-template-columns: 1fr; gap: .25rem; } .operator-info dd { margin-bottom: .75rem; } }

/* Lesson page section spacing */
.topic .chapters,
.topic .pitfalls,
.topic .share,
.topic .manual-ref { margin-top: 3rem; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  padding: .75rem 1.5rem;
  border-radius: var(--radius);
  font-weight: 700;
  transition: transform .1s, box-shadow .15s, background .15s;
  border: 2px solid transparent;
}
.btn:hover { text-decoration: none; transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-primary { background: var(--color-primary); color: #fff; }
.btn-primary:hover { background: var(--color-primary-hover); color: #fff; }
.btn-outline { border-color: var(--color-primary); color: var(--color-primary); }

/* Levels (home) */
.levels { padding: 3rem 0; }
.levels h2, .why-this-site h2, .level-section h2 { font-size: 1.75rem; color: var(--color-text-strong); margin: 0 0 1.5rem; }
.level-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}
.level-card {
  background: var(--color-surface);
  padding: 1.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  transition: box-shadow .15s, transform .1s;
}
.level-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.level-card h3 { margin-top: 0; color: var(--color-primary); display: flex; align-items: center; gap: .5rem; }
.topic-list { list-style: none; padding: 0; margin: 0; }
.topic-list li { padding: .25rem 0; border-bottom: 1px dashed var(--color-border); }
.topic-list li:last-child { border-bottom: none; }

.why-this-site { padding: 2rem 0 3rem; }

/* Topics index */
.level-section { margin: 3rem 0; }
.level-section h2 { color: var(--color-primary); border-bottom: 2px solid var(--color-primary); padding-bottom: .5rem; }
.level-desc { color: var(--color-muted); margin-bottom: 1.5rem; }
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
  padding: 0;
  list-style: none;
}
.topic-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  transition: box-shadow .15s, transform .1s;
}
.topic-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.topic-card a { display: block; padding: 1.25rem; color: var(--color-text); }
.topic-card a:hover { text-decoration: none; }
.topic-card h3 { margin: 0 0 .5rem; color: var(--color-primary); }

/* Topic page */
.breadcrumb { font-size: 0.875rem; color: var(--color-muted); padding: 1rem 0; }
.breadcrumb a { color: var(--color-muted); }
.topic-header h1 { color: var(--color-primary); font-size: clamp(1.5rem, 4vw, 2.25rem); line-height: 1.3; }
.topic-tabs { display: flex; gap: 0; border-bottom: 1px solid var(--color-border); margin-bottom: 2rem; overflow-x: auto; }
.topic-tabs a {
  padding: .75rem 1.25rem;
  color: var(--color-muted);
  border-bottom: 3px solid transparent;
  white-space: nowrap;
  font-weight: 500;
}
.topic-tabs a.active { color: var(--color-primary); border-bottom-color: var(--color-primary); font-weight: 700; }
.topic-tabs a:hover { text-decoration: none; color: var(--color-primary); }

.topic-prev-next {
  display: flex;
  justify-content: space-between;
  align-items: stretch;
  padding: 2rem 0;
  border-top: 1px solid var(--color-border);
  margin-top: 3rem;
  gap: 1rem;
}
.topic-prev-next a { display: block; padding: 1rem; border: 1px solid var(--color-border); border-radius: var(--radius); flex: 1; transition: background .15s; }
.topic-prev-next a:hover { background: var(--color-surface-alt); text-decoration: none; }
.topic-prev-next .next { text-align: right; }

/* Markdown body */
.markdown {
  max-width: var(--max-width-prose);
  font-size: 1.0625rem;
}
.markdown h1, .markdown h2, .markdown h3 { color: var(--color-text-strong); margin-top: 2.5rem; line-height: 1.4; }
.markdown h2 { border-bottom: 1px solid var(--color-border); padding-bottom: .375rem; font-size: 1.5rem; }
.markdown h3 { font-size: 1.25rem; }
.markdown p { margin: 1em 0; }
.markdown code { background: var(--color-code-bg); padding: .125rem .375rem; border-radius: 4px; font-family: var(--font-mono); font-size: .9em; }
.markdown pre { background: var(--color-code-block-bg); color: var(--color-code-block-fg); padding: 1rem; border-radius: var(--radius); overflow-x: auto; line-height: 1.5; }
.markdown pre code { background: transparent; padding: 0; color: inherit; font-size: .875rem; }
.markdown blockquote { border-left: 4px solid var(--color-accent); padding: .5rem 1rem; background: var(--color-warn-bg); color: var(--color-text); margin: 1.5rem 0; border-radius: 0 var(--radius-sm) var(--radius-sm) 0; }
.markdown table { border-collapse: collapse; width: 100%; margin: 1rem 0; font-size: .9375rem; }
.markdown th, .markdown td { border: 1px solid var(--color-border); padding: .5rem .75rem; text-align: left; }
.markdown th { background: var(--color-surface-alt); }
.markdown img { max-width: 100%; height: auto; border-radius: var(--radius-sm); }
.markdown a { text-decoration: underline; text-underline-offset: 2px; }

/* Code block with actions(Tier2-3) */
.code-block { position: relative; margin: 1.5rem 0; }
.code-block pre { margin: 0; }
.code-actions {
  display: flex;
  justify-content: flex-end;
  gap: .5rem;
  padding: .5rem;
  background: var(--color-surface-alt);
  border: 1px solid var(--color-border);
  border-top: none;
  border-radius: 0 0 var(--radius) var(--radius);
}
.code-copy, .code-run {
  display: inline-flex;
  align-items: center;
  gap: .25rem;
  padding: .375rem .75rem;
  font-size: .8125rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border-strong);
  background: var(--color-surface);
  color: var(--color-text);
  cursor: pointer;
  text-decoration: none;
  transition: background .15s;
}
.code-copy:hover, .code-run:hover { background: var(--color-code-bg); text-decoration: none; }
.code-run { background: var(--color-accent); color: #1f1300; border-color: var(--color-accent); font-weight: 700; }
.code-run:hover { background: var(--color-accent-hover); color: #1f1300; }

/* Pitfalls (Tier2-2) */
.pitfalls {
  margin: 3rem 0 2rem;
  padding: 1.5rem 1.75rem;
  background: var(--color-warn-bg);
  border-left: 5px solid var(--color-warn-border);
  border-radius: var(--radius);
}
.pitfalls h2 { display: flex; align-items: center; gap: .5rem; margin: 0 0 .5rem; font-size: 1.375rem; color: var(--color-text-strong); border: none; padding: 0; }
.pitfalls .pitfalls-icon { color: var(--color-accent-hover); }
.pitfalls-intro { color: var(--color-muted); font-size: .9375rem; margin: 0 0 1rem; }
.pitfalls-list { list-style: none; counter-reset: pitfall; padding: 0; }
.pitfall { counter-increment: pitfall; padding: .75rem 0; border-bottom: 1px dashed var(--color-border-strong); }
.pitfall:last-child { border-bottom: none; }
.pitfall h3 { font-size: 1rem; margin: 0 0 .25rem; color: var(--color-text-strong); }
.pitfall h3::before { content: counter(pitfall) ". "; color: var(--color-accent-hover); font-weight: 700; }
.pitfall p { margin: 0; color: var(--color-text); }
.pitfall code { background: rgba(255,255,255,.6); }

/* Manual ref (Tier2-1) */
.manual-ref {
  margin: 2rem 0;
  padding: 1.25rem 1.5rem;
  background: var(--color-info-bg);
  border-left: 5px solid var(--color-info-border);
  border-radius: var(--radius);
}
.manual-ref h3 { margin: 0 0 .5rem; font-size: 1.125rem; color: var(--color-text-strong); display: flex; align-items: center; gap: .5rem; }
.manual-ref p { margin: 0 0 .75rem; color: var(--color-text); font-size: .9375rem; }
.manual-link {
  display: inline-block;
  padding: .5rem 1rem;
  background: var(--color-primary);
  color: #fff !important;
  border-radius: var(--radius-sm);
  font-weight: 600;
  text-decoration: none !important;
}
.manual-link:hover { background: var(--color-primary-hover); }

/* Task list (Markdown checkbox) */
.markdown li.task { list-style: none; margin-left: -1.5em; }
.markdown li.task input[type="checkbox"] { margin-right: .5em; transform: scale(1.1); accent-color: var(--color-primary); }
.markdown li.task.done { color: var(--color-muted); text-decoration: line-through; }

/* Share buttons */
.share {
  margin: 3rem 0 2rem;
  padding: 1.25rem 1.5rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}
.share h3 { margin: 0 0 .75rem; font-size: 1.0625rem; display: flex; align-items: center; gap: .5rem; color: var(--color-text-strong); }
.share-buttons { list-style: none; padding: 0; margin: 0; display: flex; flex-wrap: wrap; gap: .5rem; }
.share-btn {
  display: inline-flex; align-items: center; gap: .35rem;
  padding: .5rem .875rem; border-radius: var(--radius-sm); font-size: .875rem; font-weight: 600;
  border: 1px solid var(--color-border-strong); background: var(--color-surface); color: var(--color-text);
  cursor: pointer; text-decoration: none; transition: transform .1s, box-shadow .15s, background .15s;
}
.share-btn:hover { transform: translateY(-1px); box-shadow: var(--shadow-sm); text-decoration: none; }
.share-btn.x        { background: #0f1419; color: #fff !important; border-color: #0f1419; }
.share-btn.hatena   { background: #00a4de; color: #fff !important; border-color: #00a4de; }
.share-btn.facebook { background: #1877f2; color: #fff !important; border-color: #1877f2; }
.share-btn.line     { background: #06c755; color: #fff !important; border-color: #06c755; }
.share-btn.pocket   { background: #ef4056; color: #fff !important; border-color: #ef4056; }
.share-btn.copy-url { background: var(--color-surface-alt); }

/* SVG figure (per-topic diagrams) */
.topic-figure {
  margin: 1.5rem 0;
  padding: 1rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  text-align: center;
}
.topic-figure svg { max-width: 100%; height: auto; }
.topic-figure figcaption { margin-top: .5rem; font-size: .875rem; color: var(--color-muted); }
/* SVG をダーク対応にするためのオーバーレイ — figure 側に明色背景を当てて常に視認可能にする */
.topic-figure img[src$=".svg"] { background: #ffffff; padding: 0.5rem; border-radius: var(--radius-sm); }
@media (prefers-color-scheme: dark) {
  .topic-figure img[src$=".svg"] { background: #f1f5f9; }
}

/* AdSense slot */
.adsense-inline { margin: 2rem 0; text-align: center; min-height: 100px; }

/* Related schools (affiliate) section */
.related-schools {
  margin: 3rem 0;
  padding: 1.5rem 1.75rem;
  background: linear-gradient(135deg, rgba(30, 58, 138, 0.05), rgba(245, 158, 11, 0.05));
  border: 2px solid var(--color-primary);
  border-radius: var(--radius);
}
.related-schools h2 {
  margin: 0 0 .5rem;
  font-size: 1.375rem;
  display: flex;
  align-items: center;
  gap: .5rem;
  border: none;
  padding: 0;
  color: var(--color-text-strong);
}
.related-schools .ad-label {
  display: inline-block;
  margin-left: auto;
  padding: .125rem .5rem;
  background: var(--color-accent);
  color: #1f1300;
  border-radius: 4px;
  font-size: .6875rem;
  font-weight: 800;
  letter-spacing: .05em;
}
.related-schools-intro { font-size: .875rem; color: var(--color-muted); margin: 0 0 1.25rem; }
.related-schools-intro strong { color: var(--color-text); font-weight: 600; }

.school-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1rem;
}
.school-item {
  position: relative;
  padding: 1.25rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  display: flex; flex-direction: column;
}
.school-item.is-self { border-color: var(--color-accent); background: linear-gradient(180deg, rgba(245, 158, 11, 0.08), var(--color-surface)); }
.self-badge {
  position: absolute; top: -.5rem; right: 1rem;
  background: var(--color-accent);
  color: #1f1300;
  padding: .125rem .5rem;
  border-radius: 999px;
  font-size: .6875rem;
  font-weight: 800;
}
.school-name { margin: 0 0 .25rem; font-size: 1.0625rem; color: var(--color-text-strong); }
.school-tagline { margin: 0 0 .5rem; font-size: .8125rem; color: var(--color-primary); font-weight: 600; }
.school-description { flex: 1; margin: 0 0 .75rem; font-size: .875rem; line-height: 1.6; }
.school-meta { display: flex; gap: 1rem; flex-wrap: wrap; margin: 0 0 .75rem; font-size: .8125rem; color: var(--color-muted); }
.school-link {
  display: inline-block; align-self: stretch; text-align: center;
  padding: .625rem 1rem;
  background: var(--color-primary);
  color: #fff !important;
  border-radius: var(--radius-sm);
  font-weight: 700;
  text-decoration: none;
  transition: background .15s;
}
.school-link:hover { background: var(--color-primary-hover); text-decoration: none; }
.school-item.is-self .school-link { background: var(--color-accent); color: #1f1300 !important; }
.school-item.is-self .school-link:hover { background: var(--color-accent-hover); }

/* Related books (affiliate) section */
.related-books {
  margin: 3rem 0;
  padding: 1.5rem 1.75rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}
.related-books h2 {
  margin: 0 0 .5rem;
  font-size: 1.375rem;
  display: flex;
  align-items: center;
  gap: .5rem;
  border: none;
  padding: 0;
  color: var(--color-text-strong);
}
.related-books .ad-label {
  display: inline-block;
  margin-left: auto;
  padding: .125rem .5rem;
  background: var(--color-accent);
  color: #1f1300;
  border-radius: 4px;
  font-size: .6875rem;
  font-weight: 800;
  letter-spacing: .05em;
}
.related-books-intro {
  font-size: .875rem;
  color: var(--color-muted);
  margin: 0 0 1.25rem;
}
.related-books-intro strong { color: var(--color-text); font-weight: 600; }

.book-list { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 1.25rem; }
.book-item { display: flex; gap: 1rem; padding: 1rem; background: var(--color-surface-alt); border-radius: var(--radius-sm); }
.book-cover { width: 96px; height: auto; flex: 0 0 96px; border-radius: 4px; background: #e2e8f0; }
.book-meta { flex: 1; min-width: 0; }
.book-title { margin: 0 0 .25rem; font-size: 1.0625rem; color: var(--color-text-strong); }
.book-author { margin: 0 0 .5rem; font-size: .8125rem; color: var(--color-muted); }
.book-description { margin: 0 0 .75rem; font-size: .9375rem; line-height: 1.6; }
.book-links { display: flex; gap: .5rem; flex-wrap: wrap; }
.book-link {
  display: inline-flex; align-items: center; gap: .25rem;
  padding: .375rem .875rem;
  border-radius: var(--radius-sm);
  font-size: .8125rem;
  font-weight: 700;
  text-decoration: none;
  border: 1px solid;
}
.book-link.amazon { background: #ff9900; color: #fff !important; border-color: #ff9900; }
.book-link.amazon:hover { background: #e88a00; text-decoration: none; }
.book-link.rakuten { background: #bf0000; color: #fff !important; border-color: #bf0000; }
.book-link.rakuten:hover { background: #a30000; text-decoration: none; }
.amazon-associate-notice { margin: 1rem 0 0; padding-top: .75rem; border-top: 1px dashed var(--color-border); color: var(--color-muted); font-size: .8125rem; line-height: 1.5; }

@media (max-width: 560px) {
  .book-item { flex-direction: column; }
  .book-cover { width: 120px; }
}

/* Reference index */
.ref-section { margin: 2.5rem 0; }
.ref-section h2 { color: var(--color-primary); border-bottom: 2px solid var(--color-primary); padding-bottom: .5rem; }
.ref-list { list-style: none; padding: 0; }
.ref-list li { padding: .5rem 0; border-bottom: 1px solid var(--color-border); }
.ref-list a {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: .25rem 1rem;
  padding: .5rem;
  border-radius: var(--radius-sm);
  color: var(--color-text);
  transition: background .15s;
}
.ref-list a:hover { background: var(--color-surface-alt); text-decoration: none; }
.ref-list code {
  grid-row: span 2;
  align-self: center;
  background: var(--color-info-bg);
  color: var(--color-primary);
  padding: .25rem .5rem;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: .875rem;
  white-space: nowrap;
}
.ref-list strong { font-size: 1rem; color: var(--color-text-strong); }
.ref-short { font-size: .875rem; color: var(--color-muted); }
.ref-related { margin: 2rem 0; padding: 1rem 1.25rem; background: var(--color-surface-alt); border-radius: var(--radius-sm); }
.ref-related h3 { margin: 0 0 .5rem; font-size: 1rem; }
.ref-note { font-size: .875rem; color: var(--color-muted); margin-top: 3rem; }

/* Cookie consent banner */
.cookie-consent {
  position: fixed;
  bottom: 1rem;
  left: 1rem;
  right: 1rem;
  margin: 0 auto;
  z-index: 9999;
  max-width: 760px;
  background: var(--color-surface);
  border: 2px solid var(--color-primary);
  border-radius: var(--radius);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
  padding: 1rem 1.25rem;
}
.cookie-consent-inner { display: flex; flex-wrap: wrap; align-items: center; gap: .75rem 1rem; justify-content: space-between; }
.cookie-consent p { margin: 0; font-size: .875rem; color: var(--color-text); flex: 1 1 320px; min-width: 0; line-height: 1.6; }
.cookie-consent p a { color: var(--color-primary); margin-left: .25rem; white-space: nowrap; }
.cookie-consent-actions { display: flex; gap: .5rem; flex: 1 1 auto; justify-content: flex-end; }
.cc-accept, .cc-reject {
  padding: .5rem 1rem;
  border-radius: var(--radius-sm);
  font-size: .875rem;
  font-weight: 700;
  cursor: pointer;
  border: 1px solid var(--color-border-strong);
  white-space: nowrap;
}
.cc-accept { background: var(--color-primary); color: #fff; border-color: var(--color-primary); }
.cc-accept:hover { background: var(--color-primary-hover); }
.cc-reject { background: var(--color-surface-alt); color: var(--color-text); }
.cc-reject:hover { background: var(--color-code-bg); }
@media (max-width: 720px) {
  .cookie-consent {
    bottom: 0; left: 0; right: 0; margin: 0;
    border-radius: 0; border-left: none; border-right: none; border-bottom: none;
    padding: .75rem 1rem; max-width: 100%;
  }
  .cookie-consent-inner { display: block; }
  .cookie-consent p { margin: 0 0 .75rem; flex: none; }
  .cookie-consent-actions { display: flex; gap: .5rem; }
  .cc-accept, .cc-reject { flex: 1 1 50%; }
}

/* Error */
.error-page { padding: 4rem 0; text-align: center; }
.error-page h1 { color: var(--color-primary); }

/* Mobile */
@media (max-width: 640px) {
  .site-header { position: static; }
  .site-header .container { flex-direction: column; gap: .5rem; padding: .25rem 1rem; }
  .site-header nav { width: 100%; justify-content: space-around; }
  .hero { padding: 2.5rem 0 2rem; }
  .hero h1 { font-size: 1.75rem; }
  .topic-tabs { flex-wrap: nowrap; }
  .topic-prev-next { flex-direction: column; }
  .topic-prev-next .next { text-align: left; }
}

/* Print(教材として印刷需要あり) */
@media print {
  .site-header, .site-footer, .code-actions, .adsense-inline, .topic-tabs, .topic-prev-next { display: none; }
  body { background: white; color: black; }
  .markdown pre { border: 1px solid #ccc; background: #f5f5f5; color: black; }
}

/* Reduce motion */
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
  html { scroll-behavior: auto; }
}