/* ============================================
   JMAR DX人材育成研修 共通スタイル
   ============================================ */

:root {
  --color-bg: #ffffff;
  --color-bg-soft: #f8fafc;
  --color-bg-card: #ffffff;
  --color-border: #e2e8f0;
  --color-border-strong: #cbd5e1;
  --color-text: #0f172a;
  --color-text-sub: #475569;
  --color-text-muted: #94a3b8;

  --color-primary: #2563eb;
  --color-primary-soft: #dbeafe;
  --color-primary-dark: #1d4ed8;
  --color-accent: #06b6d4;
  --color-purple: #8b5cf6;
  --color-green: #10b981;
  --color-amber: #f59e0b;
  --color-red: #ef4444;
  --color-pink: #ec4899;

  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.04), 0 1px 3px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 4px 6px -1px rgba(15, 23, 42, 0.08), 0 2px 4px -2px rgba(15, 23, 42, 0.06);
  --shadow-lg: 0 10px 25px -5px rgba(15, 23, 42, 0.1), 0 8px 10px -6px rgba(15, 23, 42, 0.06);

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

  --font-sans: "Inter", "Hiragino Kaku Gothic ProN", "Hiragino Sans", "Yu Gothic", Meiryo, system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", Menlo, Consolas, Monaco, "Courier New", monospace;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-sans);
  -webkit-font-smoothing: antialiased;
  line-height: 1.7;
}

a {
  color: var(--color-primary);
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}

img, svg {
  max-width: 100%;
  display: block;
}

.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ============================================
   パスワード認証ゲート
   ============================================ */
.auth-gate {
  position: fixed;
  inset: 0;
  background: linear-gradient(135deg, #f1f5f9 0%, #e0e7ff 50%, #ddd6fe 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  padding: 24px;
}
.auth-card {
  background: #fff;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-lg);
  padding: 48px 40px;
  max-width: 440px;
  width: 100%;
  text-align: center;
}
.auth-logo {
  width: 56px;
  height: 56px;
  margin: 0 auto 16px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-purple));
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 700;
  font-size: 22px;
  letter-spacing: 0.5px;
}
.auth-card h1 {
  margin: 0 0 8px;
  font-size: 22px;
  font-weight: 700;
}
.auth-card p {
  margin: 0 0 24px;
  color: var(--color-text-sub);
  font-size: 14px;
}
.auth-input {
  width: 100%;
  padding: 14px 16px;
  font-size: 16px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  outline: none;
  font-family: inherit;
  transition: border-color 0.15s;
}
.auth-input:focus {
  border-color: var(--color-primary);
}
.auth-button {
  width: 100%;
  margin-top: 12px;
  padding: 14px 20px;
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: background 0.15s, transform 0.05s;
}
.auth-button:hover { background: var(--color-primary-dark); }
.auth-button:active { transform: translateY(1px); }
.auth-error {
  margin-top: 12px;
  color: var(--color-red);
  font-size: 13px;
  min-height: 1.2em;
}

body.locked { overflow: hidden; }
body.unlocked .auth-gate { display: none; }

/* ============================================
   ヘッダー
   ============================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
}
.site-header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 0;
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  font-size: 15px;
  color: var(--color-text);
}
.brand-mark {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-purple));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 14px;
  letter-spacing: 0.5px;
}
.brand-sub {
  font-size: 12px;
  color: var(--color-text-muted);
  font-weight: 500;
  margin-top: 1px;
}
.brand-stack { display: flex; flex-direction: column; line-height: 1.2; }

.header-nav {
  display: flex;
  align-items: center;
  gap: 24px;
  font-size: 14px;
}
.header-nav a {
  color: var(--color-text-sub);
  font-weight: 500;
}
.header-nav a:hover { color: var(--color-primary); text-decoration: none; }
.header-pill {
  padding: 6px 12px;
  background: var(--color-primary-soft);
  color: var(--color-primary-dark);
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
}

/* ============================================
   ヒーロー
   ============================================ */
.hero {
  position: relative;
  padding: 80px 0 60px;
  overflow: hidden;
  background:
    radial-gradient(ellipse at top left, rgba(37, 99, 235, 0.08), transparent 50%),
    radial-gradient(ellipse at top right, rgba(139, 92, 246, 0.08), transparent 50%);
}
.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 12px;
  color: var(--color-text-sub);
  font-weight: 600;
  letter-spacing: 0.5px;
  box-shadow: var(--shadow-sm);
}
.hero-tag .dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-green);
  box-shadow: 0 0 0 4px rgba(16, 185, 129, 0.15);
}
.hero h1 {
  margin: 20px 0 16px;
  font-size: clamp(28px, 4vw, 44px);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.25;
}
.hero h1 .grad {
  background: linear-gradient(90deg, var(--color-primary), var(--color-purple), var(--color-pink));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero-lead {
  max-width: 720px;
  font-size: 16px;
  color: var(--color-text-sub);
  line-height: 1.85;
}
.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-top: 28px;
}
.hero-meta-item {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 12px 18px;
  display: flex;
  align-items: center;
  gap: 10px;
  box-shadow: var(--shadow-sm);
  font-size: 13px;
  color: var(--color-text-sub);
}
.hero-meta-item strong { color: var(--color-text); font-weight: 700; font-size: 15px; }

/* ============================================
   セクション共通
   ============================================ */
section.section {
  padding: 64px 0;
}
section.section.alt {
  background: var(--color-bg-soft);
}
.section-head {
  margin-bottom: 36px;
}
.section-eyebrow {
  display: inline-block;
  font-size: 12px;
  color: var(--color-primary);
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 8px;
}
.section-title {
  font-size: clamp(22px, 3vw, 32px);
  font-weight: 800;
  margin: 0 0 8px;
  letter-spacing: -0.01em;
}
.section-desc {
  font-size: 15px;
  color: var(--color-text-sub);
  margin: 0;
  max-width: 760px;
}

/* ============================================
   フェーズフロー
   ============================================ */
.phase-flow {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  margin-top: 32px;
}
.phase-card {
  position: relative;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px 20px;
  box-shadow: var(--shadow-sm);
}
.phase-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}
.phase-card.p1::before { background: linear-gradient(90deg, #3b82f6, #06b6d4); }
.phase-card.p2::before { background: linear-gradient(90deg, #06b6d4, #10b981); }
.phase-card.p3::before { background: linear-gradient(90deg, #8b5cf6, #ec4899); }
.phase-card.p4::before { background: linear-gradient(90deg, #f59e0b, #ef4444); }
.phase-label {
  font-size: 11px;
  font-weight: 700;
  color: var(--color-text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.phase-title {
  margin: 6px 0 4px;
  font-size: 18px;
  font-weight: 700;
}
.phase-range {
  font-size: 13px;
  color: var(--color-text-sub);
  margin-bottom: 12px;
}
.phase-keys {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.phase-keys span {
  background: var(--color-bg-soft);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  padding: 3px 10px;
  font-size: 11px;
  color: var(--color-text-sub);
}

@media (max-width: 900px) {
  .phase-flow { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 520px) {
  .phase-flow { grid-template-columns: 1fr; }
}

/* ============================================
   レッスンカード
   ============================================ */
.lessons {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 18px;
  margin-top: 32px;
}
.lesson-card {
  position: relative;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 22px 20px;
  text-decoration: none;
  color: inherit;
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-height: 180px;
}
.lesson-card.available {
  cursor: pointer;
}
.lesson-card.available:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
  text-decoration: none;
}
.lesson-card.locked {
  background: repeating-linear-gradient(
    135deg,
    #f8fafc,
    #f8fafc 8px,
    #f1f5f9 8px,
    #f1f5f9 16px
  );
  color: var(--color-text-muted);
  cursor: not-allowed;
}
.lesson-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: var(--color-primary-soft);
  color: var(--color-primary-dark);
  font-weight: 800;
  font-size: 14px;
}
.lesson-card.locked .lesson-num {
  background: #e2e8f0;
  color: var(--color-text-muted);
}
.lesson-cat {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.06em;
  padding: 3px 10px;
  border-radius: 999px;
  background: #eff6ff;
  color: #1d4ed8;
  width: fit-content;
}
.cat-intro { background: #ecfeff; color: #0e7490; }
.cat-basic { background: #eff6ff; color: #1d4ed8; }
.cat-gas { background: #ede9fe; color: #6d28d9; }
.cat-vba { background: #fef3c7; color: #b45309; }
.cat-ai { background: #fce7f3; color: #be185d; }
.cat-aigas { background: #ffe4e6; color: #be123c; }
.cat-py { background: #dcfce7; color: #15803d; }
.cat-doc { background: #ffedd5; color: #c2410c; }
.cat-final { background: #fee2e2; color: #b91c1c; }

.lesson-title {
  font-size: 16px;
  font-weight: 700;
  line-height: 1.45;
  margin: 0;
}
.lesson-summary {
  font-size: 13px;
  color: var(--color-text-sub);
  line-height: 1.65;
  margin: 0;
}
.lesson-card.locked .lesson-summary { color: var(--color-text-muted); }

.lesson-footer {
  margin-top: auto;
  padding-top: 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 12px;
  color: var(--color-text-muted);
  border-top: 1px dashed var(--color-border);
}
.lesson-card.locked .lesson-footer { border-top-style: solid; }
.lesson-arrow {
  font-weight: 700;
  color: var(--color-primary);
}
.lesson-card.locked .lesson-status {
  color: var(--color-text-muted);
  font-weight: 600;
}

/* ============================================
   フッター
   ============================================ */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: 32px 0;
  font-size: 13px;
  color: var(--color-text-muted);
  background: var(--color-bg-soft);
}
.site-footer-inner {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

/* ============================================
   詳細ページ専用
   ============================================ */
.lesson-hero {
  padding: 56px 0 36px;
  background:
    radial-gradient(ellipse at top left, rgba(37, 99, 235, 0.07), transparent 60%),
    linear-gradient(180deg, #fff, var(--color-bg-soft));
  border-bottom: 1px solid var(--color-border);
}
.breadcrumb {
  font-size: 13px;
  color: var(--color-text-muted);
  margin-bottom: 16px;
}
.breadcrumb a { color: var(--color-text-sub); }
.lesson-hero h1 {
  font-size: clamp(26px, 3.6vw, 38px);
  font-weight: 800;
  letter-spacing: -0.01em;
  margin: 8px 0 12px;
  line-height: 1.3;
}
.lesson-hero .lead {
  color: var(--color-text-sub);
  font-size: 16px;
  max-width: 780px;
}
.goal-banner {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  margin-top: 24px;
  padding: 18px 22px;
  background: linear-gradient(90deg, #eff6ff 0%, #ecfeff 100%);
  border: 1px solid #bfdbfe;
  border-radius: var(--radius-md);
}
.goal-banner .icon {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  background: var(--color-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  flex-shrink: 0;
}
.goal-banner h3 {
  font-size: 13px;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin: 0 0 4px;
  letter-spacing: 0.05em;
}
.goal-banner p {
  margin: 0;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
}

/* レイアウト: 目次 + 本文 */
.lesson-layout {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 56px;
  padding: 56px 0 80px;
}
@media (max-width: 960px) {
  .lesson-layout {
    grid-template-columns: 1fr;
    gap: 24px;
  }
}

.toc {
  position: sticky;
  top: 80px;
  align-self: start;
  font-size: 13px;
}
.toc-title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--color-text-muted);
  text-transform: uppercase;
  margin-bottom: 10px;
}
.toc ol {
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: toc;
  border-left: 2px solid var(--color-border);
}
.toc li {
  counter-increment: toc;
  padding: 7px 14px;
  position: relative;
  margin-left: 0;
}
.toc li::before {
  content: counter(toc, decimal-leading-zero);
  position: absolute;
  left: -22px;
  top: 9px;
  width: 24px;
  text-align: right;
  font-size: 11px;
  color: var(--color-text-muted);
  font-weight: 700;
  font-family: var(--font-mono);
}
.toc a {
  color: var(--color-text-sub);
  font-weight: 500;
  line-height: 1.5;
  display: block;
}
.toc a:hover { color: var(--color-primary); text-decoration: none; }

@media (max-width: 960px) {
  .toc { position: static; }
}

/* 本文 */
.lesson-content section.chapter {
  scroll-margin-top: 80px;
  margin-bottom: 56px;
}
.lesson-content h2 {
  font-size: clamp(20px, 2.4vw, 26px);
  font-weight: 800;
  margin: 0 0 8px;
  display: flex;
  align-items: center;
  gap: 12px;
  letter-spacing: -0.005em;
}
.chapter-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-purple));
  color: #fff;
  font-size: 14px;
  font-weight: 700;
  font-family: var(--font-mono);
}
.lesson-content h3 {
  font-size: 17px;
  font-weight: 700;
  margin: 28px 0 10px;
}
.lesson-content h4 {
  font-size: 15px;
  font-weight: 700;
  margin: 20px 0 8px;
  color: var(--color-text);
}
.lesson-content p {
  font-size: 15px;
  color: var(--color-text);
  margin: 12px 0;
  line-height: 1.85;
}
.lesson-content ul, .lesson-content ol {
  font-size: 15px;
  color: var(--color-text);
  line-height: 1.85;
  padding-left: 22px;
}
.lesson-content li { margin: 4px 0; }
.lesson-content strong { color: var(--color-primary-dark); font-weight: 700; }
.lesson-content em { font-style: normal; background: linear-gradient(transparent 65%, #fef9c3 65%); padding: 0 2px; font-weight: 600; }

/* キー注意・補足ボックス */
.callout {
  display: flex;
  gap: 14px;
  margin: 20px 0;
  padding: 16px 18px;
  border-radius: var(--radius-md);
  border-left: 4px solid;
  background: #fff;
}
.callout .ico {
  width: 28px;
  height: 28px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  flex-shrink: 0;
  font-size: 14px;
}
.callout p { margin: 0; font-size: 14px; line-height: 1.7; }
.callout strong { font-weight: 700; }
.callout.tip { background: #ecfeff; border-color: var(--color-accent); }
.callout.tip .ico { background: var(--color-accent); color: #fff; }
.callout.warn { background: #fffbeb; border-color: var(--color-amber); }
.callout.warn .ico { background: var(--color-amber); color: #fff; }
.callout.info { background: #eff6ff; border-color: var(--color-primary); }
.callout.info .ico { background: var(--color-primary); color: #fff; }
.callout.success { background: #ecfdf5; border-color: var(--color-green); }
.callout.success .ico { background: var(--color-green); color: #fff; }

/* コードブロック */
.code-block {
  position: relative;
  margin: 18px 0;
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 1px solid #1e293b;
  box-shadow: var(--shadow-md);
}
.code-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: #0f172a;
  color: #cbd5e1;
  padding: 10px 14px;
  font-size: 12px;
  font-family: var(--font-mono);
}
.code-header .filename {
  display: flex;
  align-items: center;
  gap: 8px;
  color: #94a3b8;
}
.code-header .dots {
  display: inline-flex;
  gap: 5px;
}
.code-header .dots span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #475569;
}
.code-header .dots span:nth-child(1) { background: #ef4444; }
.code-header .dots span:nth-child(2) { background: #f59e0b; }
.code-header .dots span:nth-child(3) { background: #10b981; }
.copy-btn {
  background: #1e293b;
  border: 1px solid #334155;
  color: #cbd5e1;
  border-radius: 6px;
  padding: 4px 10px;
  font-size: 11px;
  cursor: pointer;
  font-family: inherit;
  font-weight: 600;
  transition: background 0.15s, color 0.15s;
}
.copy-btn:hover { background: #334155; color: #fff; }
.copy-btn.copied { background: var(--color-green); color: #fff; border-color: var(--color-green); }

.code-block pre {
  margin: 0;
  background: #0f172a;
  color: #e2e8f0;
  padding: 18px 20px;
  font-family: var(--font-mono);
  font-size: 13.5px;
  line-height: 1.7;
  overflow-x: auto;
}
.code-block code { font-family: inherit; }

/* シンタックスハイライト風（手動クラス） */
.tk-kw { color: #c084fc; }      /* keyword */
.tk-fn { color: #60a5fa; }      /* function */
.tk-str { color: #86efac; }     /* string */
.tk-num { color: #fbbf24; }     /* number */
.tk-com { color: #64748b; font-style: italic; } /* comment */
.tk-var { color: #fde68a; }     /* variable */
.tk-op  { color: #f472b6; }     /* operator */
.tk-prop { color: #67e8f9; }    /* property */

/* インラインコード */
code.inline {
  font-family: var(--font-mono);
  font-size: 13px;
  background: #f1f5f9;
  border: 1px solid var(--color-border);
  padding: 1px 7px;
  border-radius: 5px;
  color: #be185d;
  white-space: nowrap;
}

/* プロンプトブロック */
.prompt-block {
  margin: 18px 0;
  background: linear-gradient(180deg, #faf5ff 0%, #fdf2f8 100%);
  border: 1px solid #e9d5ff;
  border-radius: var(--radius-md);
  overflow: hidden;
}
.prompt-header {
  background: linear-gradient(90deg, var(--color-purple), var(--color-pink));
  color: #fff;
  padding: 10px 16px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.prompt-header .label { display: flex; align-items: center; gap: 8px; }
.prompt-body {
  padding: 16px 18px;
  font-size: 14px;
  color: #4c1d95;
  line-height: 1.85;
  white-space: pre-wrap;
  font-family: var(--font-mono);
  font-size: 13px;
}
.prompt-body strong { color: #581c87; }

/* ステップ図 */
.step-diagram {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 14px;
  margin: 24px 0;
}
.step-tile {
  position: relative;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 18px;
  box-shadow: var(--shadow-sm);
}
.step-tile .num {
  position: absolute;
  top: -10px;
  left: 14px;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--color-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 700;
  border: 3px solid #fff;
}
.step-tile h5 {
  font-size: 14px;
  font-weight: 700;
  margin: 8px 0 4px;
}
.step-tile p {
  margin: 0;
  font-size: 12.5px;
  color: var(--color-text-sub);
  line-height: 1.6;
}

/* 比較テーブル */
.compare-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  margin: 16px 0;
  font-size: 14px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: #fff;
}
.compare-table th, .compare-table td {
  padding: 12px 14px;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}
.compare-table th {
  background: #f8fafc;
  font-weight: 700;
  font-size: 13px;
  color: var(--color-text-sub);
}
.compare-table tr:last-child td { border-bottom: none; }
.compare-table td code.inline { font-size: 12px; }

/* 演算子表 */
.operator-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 12px;
  margin: 16px 0;
}
.op-card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 14px 16px;
}
.op-card .sym {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 700;
  color: var(--color-primary);
  margin-right: 8px;
}
.op-card .nm {
  font-weight: 700;
  font-size: 14px;
}
.op-card .ex {
  margin-top: 6px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--color-text-sub);
}

/* 宿題セクション */
.homework {
  margin-top: 32px;
  padding: 32px;
  background: linear-gradient(135deg, #fff7ed 0%, #ffedd5 100%);
  border: 2px solid #fdba74;
  border-radius: var(--radius-lg);
}
.homework-head {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 18px;
}
.homework-badge {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: linear-gradient(135deg, #f97316, #ef4444);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  font-weight: 800;
}
.homework h2 {
  font-size: 22px;
  margin: 0;
  color: #9a3412;
}
.homework .sub {
  font-size: 13px;
  color: #c2410c;
  font-weight: 600;
}
.homework-list {
  display: grid;
  gap: 14px;
  margin-top: 16px;
}
.hw-item {
  background: #fff;
  border: 1px solid #fed7aa;
  border-radius: var(--radius-md);
  padding: 18px 20px;
  display: grid;
  grid-template-columns: 38px 1fr;
  gap: 14px;
  align-items: start;
}
.hw-num {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: #fb923c;
  color: #fff;
  font-weight: 800;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
}
.hw-item h4 {
  margin: 4px 0 6px;
  font-size: 15px;
  color: #9a3412;
}
.hw-item p {
  margin: 0;
  font-size: 13.5px;
  color: var(--color-text-sub);
  line-height: 1.75;
}

/* ナビゲーション(下部) */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid var(--color-border);
}
.nav-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-sub);
  font-size: 14px;
  font-weight: 600;
  background: #fff;
}
.nav-link:hover { border-color: var(--color-primary); color: var(--color-primary); text-decoration: none; }
.nav-link.disabled { opacity: 0.5; cursor: not-allowed; pointer-events: none; }

/* SVG 図解共通 */
.diagram {
  margin: 24px 0;
  padding: 24px;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}
.diagram-caption {
  text-align: center;
  font-size: 12.5px;
  color: var(--color-text-muted);
  margin-top: 12px;
  font-weight: 500;
}

/* ============================================
   ユーティリティ
   ============================================ */
.text-center { text-align: center; }
.mt-0 { margin-top: 0; }
.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mt-4 { margin-top: 32px; }