/* ===================================================
   CC Company 教科書サイト - v4 Universal + Modern
   大きめ文字・ゆとり間隔・日本語最適化
   Inter + Noto Sans JP / White / Navy / UD対応

   UD方針:
   - 色だけで情報を伝えない（形・太さ・テキスト併用）
   - コントラスト比 7:1+ (WCAG AAA)
   - フォーカスリング明示
   - 本文リンクに下線
   - prefers-reduced-motion 対応
   =================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&family=Noto+Sans+JP:wght@400;500;700&family=JetBrains+Mono:wght@400;500&display=swap');

/* --- Design Tokens --- */
:root {
  --color-primary: #0B3D65;
  --color-primary-light: #0D4F8B;  /* リンク色: 白背景で7.5:1 */
  --color-primary-subtle: #EBF5FF;
  --color-accent: #9E2A00;         /* warningタイトル: #FFF3E0上で8.2:1 */
  --color-accent-light: #FFF3E0;

  --color-bg: #FFFFFF;
  --color-bg-alt: #F7F9FC;
  --color-bg-code: #0F1923;
  --color-text: #171717;
  --color-text-secondary: #525252;
  --color-text-muted: #525252;     /* 旧#737373→濃く。AAA 7.1:1 on white */
  --color-border: #D4D4D8;
  --color-border-light: #E5E7EB;
  --color-white: #FFFFFF;

  --color-complete: #1565C0;
  --color-complete-light: #E3F2FD;

  --color-focus: #1565C0;
  --focus-ring: 0 0 0 3px rgba(21, 101, 192, 0.35);

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

  /* 日本語最適化サイズ */
  --text-base: 1.0625rem;   /* 17px */
  --text-sm: 0.9375rem;     /* 15px */
  --text-xs: 0.8125rem;     /* 13px */
  --text-lg: 1.1875rem;     /* 19px */
  --text-xl: 1.5rem;        /* 24px */
  --text-2xl: 2rem;         /* 32px */
  --text-3xl: 2.5rem;       /* 40px */

  --leading-body: 2.05;     /* 日本語は行間広めが読みやすい */
  --leading-heading: 1.4;
  --tracking-body: 0.03em;  /* 字間を少し空ける */
  --tracking-heading: -0.02em;

  /* Layout */
  --max-width: 1120px;
  --content-max: 740px;
  --sidebar-width: 220px;
  --header-height: 60px;

  --radius: 12px;
  --radius-sm: 8px;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.06);
  --shadow-lg: 0 12px 32px rgba(0,0,0,0.08);
}

/* --- Reset --- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 100%; scroll-behavior: smooth; -webkit-font-smoothing: antialiased; }

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  letter-spacing: var(--tracking-body);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* --- Links (UD: 下線で識別) --- */
a {
  color: var(--color-primary-light);
  text-decoration: underline;
  text-decoration-color: rgba(21,101,192,0.25);
  text-underline-offset: 3px;
  transition: all 0.2s ease-out;
}
a:hover {
  color: var(--color-primary);
  text-decoration-color: currentColor;
}

/* UD: ナビ系は位置で識別可能→下線不要（パンくずは下線維持） */
.site-header a, .course-nav a,
.sidebar a, .page-nav a, .course-card a,
.main-content ol > li > a { text-decoration: none; }
.breadcrumb a { text-decoration: underline; text-decoration-color: rgba(82,82,82,0.3); text-underline-offset: 2px; }

/* Focus ring */
a:focus-visible, button:focus-visible, [tabindex]:focus-visible {
  outline: none;
  box-shadow: var(--focus-ring);
  border-radius: 4px;
}

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

/* ===== HEADER ===== */
.site-header {
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-border-light);
  height: var(--header-height);
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
}
.header-inner {
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 0 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.site-title {
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: -0.01em;
}
.site-title a { color: var(--color-primary); }

/* --- Course Nav --- */
.course-nav { display: flex; gap: 4px; }
.course-nav a {
  font-family: var(--font-heading);
  color: var(--color-text-secondary);
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  font-weight: 600;
  transition: all 0.2s ease-out;
  cursor: pointer;
}
.course-nav a:hover {
  color: var(--color-primary);
  background: var(--color-primary-subtle);
}
.course-nav a.active {
  color: var(--color-primary);
  background: var(--color-primary-subtle);
  font-weight: 700;
}

/* --- Skip Link (a11y) --- */
.skip-link {
  position: absolute;
  top: -100%;
  left: 16px;
  z-index: 999;
  background: var(--color-primary);
  color: var(--color-white);
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  font-weight: 600;
}
.skip-link:focus {
  top: 8px;
  color: var(--color-white);
}

/* --- Reading Progress Bar --- */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: var(--color-primary);
  z-index: 150;
  width: 0;
  transition: width 60ms linear;
  pointer-events: none;
}

/* --- Course Nav Dropdown --- */
.course-nav { display: flex; gap: 2px; align-items: center; }
.course-nav-item {
  position: relative;
}
.course-nav-item > a {
  font-family: var(--font-heading);
  color: var(--color-text-secondary);
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  font-weight: 600;
  transition: color 0.2s ease-out, background 0.2s ease-out;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  white-space: nowrap;
  user-select: none;
}
.course-nav-item > a:hover,
.course-nav-item.is-open > a {
  color: var(--color-primary);
  background: var(--color-primary-subtle);
}
.course-nav-item > a.active {
  color: var(--color-primary);
  background: var(--color-primary-subtle);
  font-weight: 700;
}
/* Chevron */
.nav-chevron {
  display: inline-block;
  width: 0;
  height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-top: 4px solid currentColor;
  transition: transform 0.2s ease-out;
  margin-left: 2px;
  opacity: 0.5;
}
.course-nav-item.is-open .nav-chevron {
  transform: rotate(180deg);
}
/* Dropdown panel */
.course-nav-dropdown {
  position: absolute;
  top: calc(100% + 4px);
  left: 50%;
  transform: translateX(-50%) translateY(-4px);
  min-width: 300px;
  background: var(--color-white);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: 8px 0;
  z-index: 200;
  list-style: none;
  /* Animation */
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s ease-out, transform 0.2s ease-out, visibility 0.2s;
  pointer-events: none;
}
.course-nav-item.is-open .course-nav-dropdown {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
  pointer-events: auto;
}
.course-nav-dropdown li a {
  display: block;
  padding: 10px 20px;
  font-size: var(--text-xs);
  color: var(--color-text-secondary);
  font-weight: 500;
  transition: color 0.15s ease-out, background 0.15s ease-out;
  white-space: nowrap;
  cursor: pointer;
  line-height: 1.4;
}
.course-nav-dropdown li a:hover {
  background: var(--color-bg-alt);
  color: var(--color-primary);
}
.course-nav-dropdown li a.active {
  background: var(--color-primary-subtle);
  color: var(--color-primary);
  font-weight: 700;
  /* アクティブ左ライン */
  box-shadow: inset 3px 0 0 var(--color-primary);
}
/* Dropdown backdrop for touch dismiss */
.nav-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 150;
}
.nav-backdrop.is-active { display: block; }

/* ===== BREADCRUMB ===== */
.breadcrumb {
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 16px 32px;
  font-size: var(--text-xs);
  color: var(--color-text-muted);
}
.breadcrumb a { color: var(--color-text-muted); }
.breadcrumb a:hover { color: var(--color-primary-light); }
.breadcrumb span { margin: 0 8px; color: var(--color-border); }

/* ===== MAIN CONTENT (Top/Index) ===== */
.main-content {
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 40px 32px 80px;
  flex: 1;
}

/* ===== HEADINGS (共通) ===== */
.main-content h1,
.page-with-sidebar .content h1 {
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  font-weight: 800;
  letter-spacing: var(--tracking-heading);
  line-height: var(--leading-heading);
  color: var(--color-primary);
  margin-bottom: 24px;
}

.main-content h2,
.page-with-sidebar .content h2 {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: 700;
  letter-spacing: var(--tracking-heading);
  line-height: var(--leading-heading);
  color: var(--color-text);
  margin-top: 64px;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-border-light);
}

.main-content h3,
.page-with-sidebar .content h3 {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--color-text);
  margin-top: 40px;
  margin-bottom: 12px;
}

/* ===== BODY TEXT ===== */
.main-content p,
.page-with-sidebar .content p {
  margin-bottom: 24px;
}

/* チェックボックスリスト（各章共通） */
.page-with-sidebar .content li:has(> input[type="checkbox"]) {
  list-style-type: none !important;
  margin-left: -1.2em;
}

.main-content ul, .main-content ol,
.page-with-sidebar .content ul, .page-with-sidebar .content ol {
  margin-bottom: 24px;
  padding-left: 1.2em;
}
.main-content li,
.page-with-sidebar .content li {
  margin-bottom: 8px;
}
.main-content li p {
  margin-bottom: 6px;
  color: var(--color-text-secondary);
  font-size: var(--text-sm);
}

strong { font-weight: 700; color: var(--color-text); }

/* ===== INLINE CODE ===== */
.main-content code,
.page-with-sidebar .content code {
  background: var(--color-primary-subtle);
  color: var(--color-primary);
  padding: 3px 8px;
  border-radius: 6px;
  font-size: 0.85em;
  font-family: var(--font-mono);
  font-weight: 500;
  letter-spacing: 0;
}

/* ===== CODE BLOCKS (UD: 白背景+黒文字で最大コントラスト) ===== */
.main-content pre,
.page-with-sidebar .content pre {
  background: var(--color-bg-alt);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  padding: 28px 32px;
  border-radius: var(--radius);
  overflow-x: auto;
  margin-bottom: 28px;
  font-size: var(--text-base);
  line-height: 1.9;
  letter-spacing: 0.01em;
}
.main-content pre code,
.page-with-sidebar .content pre code {
  background: none;
  padding: 0;
  color: inherit;
  font-weight: 400;
  font-family: var(--font-body);
}

/* ===== TABLES ===== */
.main-content table,
.page-with-sidebar .content table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  margin-bottom: 28px;
  font-size: var(--text-sm);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-sm);
  overflow: hidden;
}
.main-content th,
.page-with-sidebar .content th {
  background: var(--color-bg-alt);
  font-weight: 600;
  text-align: left;
  padding: 14px 20px;
  border-bottom: 2px solid var(--color-border);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-secondary);
}
.main-content td,
.page-with-sidebar .content td {
  padding: 14px 20px;
  border-bottom: 1px solid var(--color-border-light);
  vertical-align: top;
}
.main-content tr:last-child td,
.page-with-sidebar .content tr:last-child td {
  border-bottom: none;
}
.main-content tr:hover td,
.page-with-sidebar .content tr:hover td {
  background: var(--color-bg-alt);
}

/* ===== INFO CARDS (テーブル代替・スマホファースト) ===== */
.info-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  margin-bottom: 28px;
}
.info-card {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius);
  padding: 24px 28px;
  transition: box-shadow 0.2s ease-out;
}
.info-card:hover {
  box-shadow: var(--shadow-sm);
}
.info-card-title {
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-border-light);
}
.info-card dl {
  margin: 0;
}
.info-card dt {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 4px;
}
.info-card dd {
  margin: 0 0 16px 0;
  font-size: var(--text-sm);
  line-height: 1.8;
  color: var(--color-text);
}
.info-card dd:last-child {
  margin-bottom: 0;
}

/* ===== CALLOUTS (UD: 色+形+テキスト) ===== */
.callout {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border-light);
  border-left: 4px solid var(--color-primary);
  padding: 24px 28px;
  margin-bottom: 28px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
.callout.warning {
  border-left-color: var(--color-accent);
  border-left-style: dashed;  /* UD: 実線→破線で形状差を追加 */
  background: var(--color-accent-light);
  border-color: rgba(158,42,0,0.15);
  border-left-color: var(--color-accent);
}
.callout-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: var(--text-sm);
  margin-bottom: 8px;
  color: var(--color-primary);
}
.callout.warning .callout-title { color: var(--color-accent); }
.callout p {
  font-size: var(--text-sm);
  margin-bottom: 0;
  color: var(--color-text-secondary);
  line-height: 1.85;
}
.callout p:not(:last-child) { margin-bottom: 12px; }

/* ===== COURSE CARDS ===== */
.course-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
  margin: 48px 0;
}
.course-card {
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius);
  padding: 36px 32px;
  transition: all 0.25s ease-out;
  cursor: pointer;
  background: var(--color-bg);
}
.course-card:hover {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-lg);
  transform: translateY(-4px);
}
.course-card h3 {
  font-family: var(--font-heading);
  margin-top: 12px;
  margin-bottom: 12px;
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: var(--tracking-heading);
}
.course-card .course-label {
  display: inline-block;
  background: var(--color-primary-subtle);
  color: var(--color-primary);
  font-family: var(--font-heading);
  font-size: var(--text-xs);  /* UD: 11px→13px */
  font-weight: 700;
  padding: 4px 14px;
  border-radius: 100px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.course-card p {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  margin-bottom: 20px;
  line-height: 1.8;
}
.course-card .card-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--color-primary);
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: var(--text-sm);
  transition: gap 0.2s ease-out;
}
.course-card:hover .card-link {
  gap: 12px;
  color: var(--color-primary-light);
}

/* ===== PAGE INDEX LIST ===== */
.main-content ol > li {
  padding: 20px 0;
  border-bottom: 1px solid var(--color-border-light);
}
.main-content ol > li:last-child { border-bottom: none; }
.main-content ol > li > a {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 600;
}

/* ===== PAGE NAV (Prev/Next) — 均等幅 ===== */
.page-nav {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 64px;
  padding-top: 24px;
  border-top: 1px solid var(--color-border-light);
}
.page-nav a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-sm);
  transition: border-color 0.15s ease-out, background 0.15s ease-out;
  cursor: pointer;
  font-family: var(--font-heading);
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-text-secondary);
  white-space: nowrap;
}
.page-nav a:hover {
  border-color: var(--color-primary-light);
  background: var(--color-bg-alt);
  color: var(--color-primary);
}
.page-nav .nav-label {
  color: inherit;
}
.page-nav .nav-title { display: none; }
.page-nav .prev { margin-right: auto; }
.page-nav .next { margin-left: auto; }

/* ===== SIDEBAR LAYOUT ===== */
.page-with-sidebar {
  display: flex;
  gap: 56px;
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 32px 32px 80px;
  flex: 1;
}
.page-with-sidebar .sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
}
.page-with-sidebar .sidebar nav {
  position: sticky;
  top: calc(var(--header-height) + 24px);
}
.page-with-sidebar .sidebar .sidebar-label {
  font-family: var(--font-heading);
  font-size: var(--text-xs);  /* UD: 11px→13px */
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 16px;
  font-weight: 700;
}
.page-with-sidebar .sidebar ul { list-style: none; padding: 0; }
.page-with-sidebar .sidebar li { margin-bottom: 2px; }
.page-with-sidebar .sidebar a {
  display: block;
  padding: 8px 12px;
  font-size: var(--text-xs);
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  transition: color 0.15s ease-out, background 0.15s ease-out, box-shadow 0.15s ease-out;
  line-height: 1.5;
  font-weight: 500;
  cursor: pointer;
}
.page-with-sidebar .sidebar a:hover {
  background: var(--color-bg-alt);
  color: var(--color-primary);
}
.page-with-sidebar .sidebar a.active {
  color: var(--color-primary);
  font-weight: 600;
  box-shadow: inset 2px 0 0 var(--color-border);
}
.page-with-sidebar .sidebar ul {
  max-height: calc(100vh - 240px);
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--color-border) transparent;
}
/* サイドバーグループ区切り */
.sidebar-group-label {
  font-family: var(--font-heading);
  font-size: 10px;
  font-weight: 700;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  padding: 12px 12px 4px;
  margin-top: 8px;
  border-top: 1px solid var(--color-border-light);
  user-select: none;
}
.sidebar-group-label:first-child {
  margin-top: 0;
  border-top: none;
  padding-top: 4px;
}
.page-with-sidebar .content {
  flex: 1;
  min-width: 0;
  max-width: var(--content-max);
}


/* ===== STEP INDICATOR ===== */
.step-indicator {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 24px;
  font-size: var(--text-xs);
  color: var(--color-text-muted);
}
.step-indicator .step { display: flex; align-items: center; gap: 4px; }
.step-indicator .step-number {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--color-border);
  color: var(--color-white);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
  font-family: var(--font-heading);
}
.step-indicator .step.active .step-number { background: var(--color-primary); }
.step-indicator .step.done .step-number { background: var(--color-complete); }
.step-indicator .step-line { width: 28px; height: 2px; background: var(--color-border); }

/* ===== FOOTER ===== */
.site-footer {
  background: var(--color-bg-alt);
  border-top: 1px solid var(--color-border-light);
  padding: 40px 32px;
  text-align: center;
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  margin-top: auto;
}

/* ===== HAMBURGER BUTTON ===== */
.hamburger-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  border-radius: var(--radius-sm);
  transition: background 0.15s ease-out;
  color: var(--color-text);
}
.hamburger-btn:hover { background: var(--color-bg-alt); }
.hamburger-btn svg { display: block; }

/* ===== MOBILE DRAWER ===== */
.mobile-drawer {
  display: none;
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: 300px;
  max-width: 85vw;
  background: var(--color-white);
  z-index: 300;
  box-shadow: var(--shadow-lg);
  transform: translateX(100%);
  transition: transform 0.25s ease-out;
  overflow-y: auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
}
.mobile-drawer.is-open { transform: translateX(0); }
.mobile-drawer-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.3);
  z-index: 250;
  opacity: 0;
  transition: opacity 0.25s ease-out;
}
.mobile-drawer-backdrop.is-open { opacity: 1; }

.mobile-drawer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--color-border-light);
}
.mobile-drawer-title {
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-primary);
}
.mobile-drawer-close {
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  transition: background 0.15s ease-out;
}
.mobile-drawer-close:hover { background: var(--color-bg-alt); }

.mobile-drawer-body { padding: 12px 0; }
.mobile-drawer-group {
  padding: 0 16px;
}
.mobile-drawer-group-label {
  font-family: var(--font-heading);
  font-size: 10px;
  font-weight: 700;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: 12px 8px 4px;
  margin-top: 4px;
  border-top: 1px solid var(--color-border-light);
}
.mobile-drawer-group:first-child .mobile-drawer-group-label {
  border-top: none;
  margin-top: 0;
}
.mobile-drawer-group a {
  display: block;
  padding: 10px 8px;
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: color 0.15s ease-out, background 0.15s ease-out;
  cursor: pointer;
}
.mobile-drawer-group a:hover {
  color: var(--color-primary);
  background: var(--color-bg-alt);
}
.mobile-drawer-group a.active {
  color: var(--color-primary);
  font-weight: 600;
  box-shadow: inset 2px 0 0 var(--color-border);
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  :root { --header-height: 52px; }

  .header-inner {
    flex-direction: row;
    padding: 0 16px;
    height: var(--header-height);
  }
  /* ヘッダーナビ非表示、ハンバーガー表示 */
  .course-nav { display: none; }
  .hamburger-btn { display: block; }
  .mobile-drawer { display: block; }
  .mobile-drawer-backdrop { display: block; pointer-events: none; }
  .mobile-drawer-backdrop.is-open { pointer-events: auto; }

  /* サイドバー非表示（ドロワーに統合） */
  .page-with-sidebar .sidebar { display: none !important; }
  .sidebar-group-label { display: none !important; }

  .main-content { padding: 24px 20px 48px; }

  .main-content h1,
  .page-with-sidebar .content h1 { font-size: var(--text-xl); }
  .main-content h2,
  .page-with-sidebar .content h2 { font-size: var(--text-lg); margin-top: 40px; }

  .page-with-sidebar {
    display: block;
    padding: 20px 20px 48px;
  }
  .page-with-sidebar .content {
    width: 100%;
    max-width: 100%;
  }

  .course-cards { grid-template-columns: 1fr; }

  .breadcrumb { padding: 12px 20px; }
}

/* ===== PRINT ===== */
@media print {
  .site-header, .sidebar, .page-nav, .site-footer { display: none; }
  .page-with-sidebar { display: block; }
  .page-with-sidebar .content { max-width: 100%; }
  body { font-size: 12pt; line-height: 1.8; }
}

/* ===== REDUCED MOTION ===== */
@media (prefers-reduced-motion: reduce) {
  * { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}