/* =========================================================
   有AI了還有學甚麼? — AI·SEO·GEO·AEO 專屬知識課程 (style.css)
   架構：純 HTML5 + CSS3 + Vanilla JS，無框架
   編碼：UTF-8 繁體中文
   基底：參考「營養綠手指 web-nutrition-basics」設計系統
   ========================================================= */

/* ---------- 0. Reset & 變數 ---------- */
:root {
  --c-primary: #2563eb;
  --c-primary-dark: #1e40af;
  --c-primary-light: #eef4ff;
  --c-accent: #d97706;
  --c-accent-light: #fef3c7;
  --c-ink: #172036;
  --c-ink-2: #3b465e;
  --c-ink-3: #6b7690;
  --c-line: #e2e8f0;
  --c-bg: #fafbfd;
  --c-bg-soft: #f1f4fa;
  --c-card: #ffffff;
  --c-danger: #b91c1c;
  --radius: 10px;
  --radius-lg: 16px;
  --shadow: 0 1px 3px rgba(23,32,54,.08), 0 4px 14px rgba(23,32,54,.06);
  --shadow-lg: 0 6px 24px rgba(23,32,54,.12);
  --maxw: 1180px;
  --font: "Noto Sans TC", "Microsoft JhengHei", "PingFang TC", "Heiti TC", sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0; font-family: var(--font); color: var(--c-ink);
  background: var(--c-bg); line-height: 1.75; font-size: 16px;
}
img { max-width: 100%; display: block; height: auto; }
a { color: var(--c-primary); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { line-height: 1.35; color: var(--c-ink); margin: 0 0 .6em; font-weight: 700; }
h1 { font-size: clamp(1.6rem, 3.5vw, 2.4rem); }
h2 { font-size: clamp(1.3rem, 2.6vw, 1.7rem); }
h3 { font-size: 1.15rem; }
p { margin: 0 0 1em; }
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }
.skip-link { position: absolute; left: -9999px; top: 0; background: var(--c-primary); color: #fff; padding: 8px 16px; z-index: 999; }
.skip-link:focus { left: 10px; }

/* 閱讀進度條 */
.read-progress { position: fixed; top: 0; left: 0; height: 3px; width: 0%; background: var(--c-accent); z-index: 999; transition: width .1s; }

/* ---------- 1. 頂端列 + MegaMenu ---------- */
.site-header {
  background: var(--c-card); border-bottom: 1px solid var(--c-line);
  position: sticky; top: 0; z-index: 200;
}
.header-bar { display: flex; align-items: center; gap: 18px; padding: 12px 20px; max-width: var(--maxw); margin: 0 auto; position: relative; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; font-size: 1.1rem; color: var(--c-ink); white-space: nowrap; }
.brand:hover { text-decoration: none; }
.brand-mark { width: 36px; height: 36px; flex: 0 0 36px; }
.brand small { display: block; font-size: .7rem; font-weight: 500; color: var(--c-ink-3); letter-spacing: .05em; }
.brand .brand-en { display: block; font-size: .66rem; font-weight: 500; color: var(--c-ink-3); letter-spacing: .1em; }

.main-nav { display: flex; align-items: center; gap: 4px; margin-left: auto; }
.nav-item { position: relative; }
.nav-link { display: block; padding: 10px 14px; color: var(--c-ink-2); font-weight: 600; border-radius: 8px; font-size: .95rem; }
.nav-link:hover, .nav-item.active > .nav-link { background: var(--c-primary-light); color: var(--c-primary-dark); text-decoration: none; }

.mega {
  position: absolute; top: 100%; left: 50%; transform: translateX(-5%) translateY(8px);
  background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg); padding: 18px; min-width: 560px; max-width: 90vw;
  opacity: 0; visibility: hidden; transition: all .2s ease; z-index: 300;
}
.nav-item:hover .mega, .nav-item:focus-within .mega { opacity: 1; visibility: visible; transform: translateX(-5%) translateY(0); }
.mega-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 6px 20px; }
.mega-col h4 { font-size: .8rem; text-transform: uppercase; letter-spacing: .08em; color: var(--c-primary); margin: 0 0 8px; }
.mega-col a { display: block; padding: 6px 8px; border-radius: 6px; color: var(--c-ink-2); font-size: .92rem; }
.mega-col a:hover { background: var(--c-bg-soft); text-decoration: none; color: var(--c-primary-dark); }
.mega-col a small { display: block; color: var(--c-ink-3); font-size: .75rem; font-weight: 400; }

.nav-toggle { display: none; background: none; border: 1px solid var(--c-line); border-radius: 8px; padding: 8px 12px; font-size: 1.2rem; cursor: pointer; }

/* ---------- 3. Hero ---------- */
.hero {
  position: relative; overflow: hidden; color: #fff;
  min-height: 420px; display: flex; align-items: center;
  background: linear-gradient(135deg, #0c1a3a 0%, #16305e 55%, #1e40af 100%);
}
.hero::after {
  content: ""; position: absolute; inset: 0; z-index: 1;
  background: radial-gradient(ellipse 60% 50% at 80% 20%, rgba(255,255,255,.10), transparent 60%);
}
.hero > .container { position: relative; z-index: 2; width: 100%; padding: 60px 0; text-align: center; }
.hero h1 { color: #fff; font-size: 2.4rem; line-height: 1.2; text-shadow: 0 2px 12px rgba(0,0,0,.3); }
.hero p.lead { font-size: 1.15rem; max-width: 680px; margin: 14px auto 0; color: rgba(255,255,255,.95); }
.hero-tags { margin-top: 20px; display: flex; flex-wrap: wrap; justify-content: center; gap: 8px; }
.hero-tags .tag { background: rgba(255,255,255,.15); color: #fff; border: 1px solid rgba(255,255,255,.3); backdrop-filter: blur(4px); }
.hero-eyebrow { font-size: .85rem; letter-spacing: .3em; color: var(--c-accent-light); margin-bottom: 12px; }

/* ---------- 4. 麵包屑 ---------- */
.breadcrumb { font-size: .85rem; padding: 14px 0; color: var(--c-ink-3); }
.breadcrumb ol { list-style: none; padding: 0; margin: 0; display: flex; flex-wrap: wrap; gap: 6px; }
.breadcrumb li + li::before { content: "›"; margin-right: 6px; color: var(--c-line); }
.breadcrumb a { color: var(--c-ink-2); }
.breadcrumb [aria-current="page"] { color: var(--c-ink); font-weight: 600; }

/* ---------- 5. 主體版面 ---------- */
.layout { display: grid; grid-template-columns: 1fr 280px; gap: 32px; padding: 24px 0 60px; }
.layout.single { grid-template-columns: 1fr; }
.content-main { min-width: 0; }

/* ---------- 6. 卡片網格 ---------- */
.card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin: 20px 0; }
.topic-card {
  background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-lg);
  padding: 22px; box-shadow: var(--shadow); transition: transform .15s, box-shadow .15s; display: block; color: var(--c-ink);
}
.topic-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); text-decoration: none; }
.topic-card .card-icon { width: 44px; height: 44px; border-radius: 10px; background: var(--c-primary-light); display: flex; align-items: center; justify-content: center; margin-bottom: 12px; color: var(--c-primary); }
.topic-card h3 { margin-bottom: 6px; }
.topic-card p { color: var(--c-ink-3); font-size: .9rem; margin: 0 0 10px; }

/* ---------- 7. Accordion ---------- */
.accordion { border: 1px solid var(--c-line); border-radius: var(--radius-lg); background: var(--c-card); margin: 16px 0; overflow: hidden; }
.acc-item { border-bottom: 1px solid var(--c-line); }
.acc-item:last-child { border-bottom: 0; }
.acc-head {
  width: 100%; text-align: left; background: none; border: 0; padding: 16px 20px;
  font-size: 1rem; font-weight: 700; color: var(--c-ink); cursor: pointer;
  display: flex; justify-content: space-between; align-items: center; font-family: var(--font);
}
.acc-head:hover { background: var(--c-bg-soft); }
.acc-head .acc-arrow { transition: transform .2s; color: var(--c-ink-3); font-size: .8rem; }
.acc-item.open .acc-head .acc-arrow { transform: rotate(180deg); }
.acc-body { max-height: 0; overflow: hidden; transition: max-height .3s ease; }
.acc-item.open .acc-body { max-height: 2000px; }
.acc-inner { padding: 4px 20px 20px; color: var(--c-ink-2); }
.acc-inner ul { padding-left: 20px; margin: 8px 0; }
.acc-inner li { margin-bottom: 6px; }

/* ---------- 8. Sidebar ---------- */
.sidebar { display: flex; flex-direction: column; gap: 20px; }
.side-box { background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-lg); padding: 18px; }
.side-box h3 { font-size: .9rem; text-transform: uppercase; letter-spacing: .06em; color: var(--c-primary); margin-bottom: 12px; }
.toc-list { list-style: none; padding: 0; margin: 0; }
.toc-list li { margin-bottom: 2px; }
.toc-list a { display: block; padding: 6px 10px; border-radius: 6px; color: var(--c-ink-2); font-size: .88rem; border-left: 3px solid transparent; }
.toc-list a:hover, .toc-list a.active { background: var(--c-primary-light); color: var(--c-primary-dark); border-left-color: var(--c-primary); text-decoration: none; }
.toc-list .toc-sub { padding-left: 22px; font-size: .82rem; }

.treemap { display: grid; grid-template-columns: repeat(2, 1fr); gap: 6px; font-size: .78rem; }
.treemap a { display: flex; align-items: center; justify-content: center; text-align: center; padding: 14px 8px; border-radius: 8px; color: #fff; font-weight: 600; min-height: 56px; }
.treemap a:hover { text-decoration: none; filter: brightness(1.1); }
.tm-1 { background: #2563eb; } .tm-2 { background: #0891b2; }
.tm-3 { background: #d97706; } .tm-4 { background: #7c3aed; }

.tag-cloud { display: flex; flex-wrap: wrap; gap: 6px; }
.tag { display: inline-block; padding: 4px 12px; border-radius: 999px; font-size: .8rem; background: var(--c-bg-soft); color: var(--c-ink-2); border: 1px solid var(--c-line); }
.tag:hover, .tag.active { background: var(--c-primary); color: #fff; border-color: var(--c-primary); text-decoration: none; }

/* ---------- 9. 知識圖譜 SVG ---------- */
.graph-wrap { background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-lg); padding: 20px; margin: 20px 0; }
.graph-svg { width: 100%; height: auto; }
.graph-node { cursor: pointer; }
.graph-node circle { fill: var(--c-primary-light); stroke: var(--c-primary); stroke-width: 2; transition: all .2s; }
.graph-node:hover circle { fill: var(--c-primary); }
.graph-node:hover text { fill: #fff; }
.graph-node text { font-size: 12px; fill: var(--c-ink); font-family: var(--font); text-anchor: middle; }
.graph-link { stroke: var(--c-line); stroke-width: 1.5; }

/* ---------- 10. 課程卡片 ---------- */
.course-card {
  background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-lg);
  overflow: hidden; box-shadow: var(--shadow); transition: transform .15s, box-shadow .15s;
  display: flex; flex-direction: column;
}
.course-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.course-card-head { padding: 20px 20px 4px; }
.course-card-head .pill { display: inline-block; padding: 2px 12px; border-radius: 999px; font-size: .72rem; font-weight: 700; color: #fff; background: var(--c-primary); margin-bottom: 10px; }
.course-card-head .pill.geo { background: #0891b2; }
.course-card-head .pill.aeo { background: #d97706; }
.course-card-title { font-size: 1.2rem; font-weight: 700; margin-bottom: 6px; color: var(--c-ink); }
.course-card-desc { font-size: .88rem; color: var(--c-ink-2); margin-bottom: 12px; }
.course-card-body { padding: 4px 20px 20px; flex: 1; display: flex; flex-direction: column; }
.course-card-meta { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 14px; }
.course-tag { display: inline-block; padding: 2px 10px; border-radius: 999px; font-size: .72rem; background: var(--c-bg-soft); color: var(--c-ink-3); border: 1px solid var(--c-line); }
.course-cta { margin-top: auto; display: inline-flex; align-items: center; gap: 6px; color: var(--c-primary); font-weight: 700; }
.course-cta:hover { text-decoration: none; color: var(--c-primary-dark); }

/* 三柱介紹（SEO/GEO/AEO） */
.pillars { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin: 20px 0; }
.pillar { background: var(--c-card); border: 1px solid var(--c-line); border-radius: var(--radius-lg); padding: 22px; box-shadow: var(--shadow); }
.pillar .pillar-en { font-size: .72rem; letter-spacing: .18em; color: var(--c-primary); font-weight: 700; margin-bottom: 6px; }
.pillar h3 { margin-bottom: 8px; }
.pillar p { color: var(--c-ink-3); font-size: .9rem; margin: 0; }

/* ---------- 11. Callout & 表格 ---------- */
.lead { font-size: 1.08rem; color: var(--c-ink-2); }
.callout { background: var(--c-primary-light); border-left: 4px solid var(--c-primary); padding: 14px 18px; border-radius: 0 8px 8px 0; margin: 16px 0; }
.callout.warn { background: var(--c-accent-light); border-left-color: var(--c-accent); }
.table-wrap { overflow-x: auto; margin: 16px 0; }
table.data { width: 100%; border-collapse: collapse; background: var(--c-card); border-radius: var(--radius); overflow: hidden; font-size: .9rem; }
table.data th, table.data td { padding: 10px 14px; border: 1px solid var(--c-line); text-align: left; }
table.data th { background: var(--c-bg-soft); font-weight: 700; }
.meta { font-size: .82rem; color: var(--c-ink-3); }
.steps { counter-reset: step; list-style: none; padding: 0; margin: 16px 0; }
.steps li { position: relative; padding: 12px 0 12px 48px; border-bottom: 1px solid var(--c-line); }
.steps li::before { counter-increment: step; content: counter(step); position: absolute; left: 0; top: 12px; width: 32px; height: 32px; border-radius: 50%; background: var(--c-primary); color: #fff; font-weight: 700; display: flex; align-items: center; justify-content: center; }

/* ---------- 12. 浮動導覽 ---------- */
.floating-nav { position: fixed; right: 18px; bottom: 18px; display: flex; flex-direction: column; gap: 8px; z-index: 500; }
.fab { width: 46px; height: 46px; border-radius: 50%; background: var(--c-primary); color: #fff; border: 0; cursor: pointer; box-shadow: var(--shadow-lg); font-size: 1.1rem; display: flex; align-items: center; justify-content: center; transition: transform .15s; }
.fab:hover { transform: translateY(-2px); background: var(--c-primary-dark); }
.fab.secondary { background: var(--c-card); color: var(--c-primary); border: 1px solid var(--c-line); }

/* ---------- 13. 深色模式 ---------- */
[data-theme="dark"] {
  --c-ink: #e8eef8; --c-ink-2: #b8c3d8; --c-ink-3: #7d8aa6;
  --c-line: #2a3450; --c-bg: #10151f; --c-bg-soft: #1a2233;
  --c-card: #1a2233; --c-primary-light: #1e2a4a;
}
[data-theme="dark"] .site-header { background: var(--c-card); }
[data-theme="dark"] .hero { background: linear-gradient(135deg, #0c1a3a, #1e40af); }

/* ---------- 14. Footer ---------- */
.site-footer { background: var(--c-ink); color: rgba(255,255,255,.75); padding: 40px 0 24px; margin-top: 40px; font-size: .88rem; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 24px; }
.site-footer h4 { color: #fff; font-size: .95rem; margin-bottom: 12px; }
.site-footer a { color: rgba(255,255,255,.75); display: block; padding: 3px 0; }
.site-footer a:hover { color: #fff; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.15); margin-top: 28px; padding-top: 18px; text-align: center; font-size: .8rem; color: rgba(255,255,255,.5); }

/* ---------- 15. RWD ---------- */
@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  .card-grid, .pillars { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .mega { position: static; transform: none; min-width: 100%; display: none; }
  .nav-item.open .mega { display: block; opacity: 1; visibility: visible; transform: none; }
  .main-nav { display: none; }
  .main-nav.open { display: flex; position: absolute; top: 100%; left: 0; right: 0; flex-direction: column; background: var(--c-card); border-bottom: 1px solid var(--c-line); padding: 12px 20px; }
  .nav-toggle { display: block; margin-left: auto; }
}
@media (max-width: 520px) {
  .card-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  body { font-size: 15px; }
  .hero > .container { padding: 44px 18px; }
  .hero h1 { font-size: 1.7rem; }
  .container { padding: 0 16px; }
}

/* ---------- 16. 列印 ---------- */
@media print {
  .site-header, .floating-nav, .sidebar { display: none !important; }
  body { font-size: 12pt; color: #000; background: #fff; }
  a { color: #000; text-decoration: underline; }
}