/* ===========================================
   典陸教育集團 ‧ 國中自然．歷屆考題網頁好讀版
   Mobile-first, danlu-education palette inspired
   =========================================== */

:root {
  --teal-700: #1B7A75;
  --teal-600: #2AADA4;
  --teal-500: #3DC2B7;
  --teal-100: #E4F5F3;
  --teal-50:  #F3FAFA;
  --slate-700: #2d5a7a;
  --slate-500: #6b7f93;
  --ink: #1A2530;
  --grey-700: #4a4a4a;
  --grey-500: #8B8B8B;
  --grey-300: #DEE2E6;
  --grey-100: #F7F8FC;
  --paper: #FAFCFC;
  --gold: #C9A66B;
  --red: #C1382E;
  --white: #FFFFFF;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { -webkit-text-size-adjust: 100%; }

body {
  font-family: "Noto Sans TC", "PingFang TC", "Hiragino Sans GB",
               "Microsoft JhengHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: var(--teal-600); text-decoration: none; }
a:hover { color: var(--teal-700); }

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

/* ==== Header ==== */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: var(--white);
  border-bottom: 1px solid var(--grey-300);
  box-shadow: 0 1px 4px rgba(0,0,0,.04);
}
.site-header-inner {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 1100px; margin: 0 auto;
  padding: 12px 18px;
}
.brand {
  display: flex; align-items: center; gap: 10px;
  text-decoration: none; color: var(--ink);
}
.brand-mark {
  width: 38px; height: 38px;
  background: var(--teal-600);
  color: white;
  font-weight: 700; font-size: 16px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 8px;
  letter-spacing: -1px;
}
.brand-name { font-weight: 700; font-size: 17px; line-height: 1.1; }
.brand-tag  { font-size: 11px; color: var(--slate-500); margin-top: 2px; }

.site-nav { display: none; gap: 22px; align-items: center; }
.site-nav a { font-size: 14px; color: var(--grey-700); font-weight: 500; }
.site-nav a:hover, .site-nav a.active { color: var(--teal-600); }

@media (min-width: 720px) {
  .site-nav { display: flex; }
}

/* ==== Hero ==== */
.hero {
  background: linear-gradient(135deg, #F3FAFA 0%, #E4F5F3 100%);
  padding: 56px 18px 64px;
  border-bottom: 1px solid var(--teal-100);
  position: relative; overflow: hidden;
}
.hero::before {
  content: ""; position: absolute;
  top: -80px; right: -80px;
  width: 280px; height: 280px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(42,173,164,0.18), transparent 70%);
}
.hero-inner { max-width: 1100px; margin: 0 auto; position: relative; }
.hero-eyebrow {
  display: inline-block;
  padding: 4px 12px;
  background: var(--teal-600);
  color: white;
  font-size: 12px; font-weight: 600;
  border-radius: 20px;
  letter-spacing: 0.5px;
  margin-bottom: 16px;
}
.hero h1 {
  font-size: 28px; line-height: 1.25;
  font-weight: 700;
  color: var(--ink);
}
.hero h1 .hl { color: var(--teal-700); }
.hero p.lead {
  margin-top: 12px;
  font-size: 15px; color: var(--grey-700);
  max-width: 540px;
}
.hero-stats {
  display: flex; gap: 28px; margin-top: 28px; flex-wrap: wrap;
}
.hero-stats .stat .num {
  font-size: 28px; font-weight: 700; color: var(--teal-600);
}
.hero-stats .stat .lbl {
  font-size: 13px; color: var(--slate-500); margin-top: 2px;
}

@media (min-width: 720px) {
  .hero h1 { font-size: 38px; }
  .hero { padding: 88px 18px 96px; }
}

/* ==== Section ==== */
.section { max-width: 1100px; margin: 0 auto; padding: 48px 18px; }
.section-title {
  display: flex; align-items: baseline; gap: 12px;
  margin-bottom: 24px;
}
.section-title h2 {
  font-size: 22px; font-weight: 700; color: var(--ink);
  position: relative; padding-left: 14px;
}
.section-title h2::before {
  content: ""; position: absolute; left: 0; top: 6px;
  width: 4px; height: 22px;
  background: var(--teal-600); border-radius: 2px;
}
.section-title small { color: var(--slate-500); font-size: 13px; }

/* ==== Volume Cards (Index) ==== */
.vol-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
}
@media (min-width: 720px) {
  .vol-grid { grid-template-columns: repeat(3, 1fr); gap: 24px; }
}

.vol-card {
  background: white;
  border-radius: 16px;
  padding: 28px 24px;
  border: 1px solid var(--grey-300);
  transition: all .25s ease;
  display: block; color: inherit;
  position: relative; overflow: hidden;
}
.vol-card:hover {
  transform: translateY(-3px);
  border-color: var(--teal-600);
  box-shadow: 0 12px 28px rgba(42,173,164,0.18);
}
.vol-card .roman {
  font-family: "Times New Roman", "Noto Serif TC", serif;
  font-size: 64px; line-height: 1;
  color: var(--teal-600);
  font-weight: 700;
}
.vol-card .vc-title {
  font-size: 19px; font-weight: 700; margin-top: 8px; color: var(--ink);
}
.vol-card .vc-sub {
  font-size: 13px; color: var(--slate-500); margin-top: 4px;
}
.vol-card .vc-meta {
  display: flex; gap: 16px; margin-top: 16px;
  padding-top: 16px; border-top: 1px solid var(--grey-300);
  font-size: 13px; color: var(--grey-700);
}
.vol-card .vc-meta b { color: var(--teal-700); margin-right: 4px; }
.vol-card .vc-cta {
  margin-top: 18px; display: inline-flex; align-items: center; gap: 6px;
  font-size: 14px; font-weight: 600; color: var(--teal-600);
}
.vol-card .vc-cta svg { width: 14px; height: 14px; }

/* ==== Chapter list ==== */
.ch-list { display: flex; flex-direction: column; gap: 10px; }
.ch-row {
  display: flex; align-items: center; gap: 16px;
  background: white;
  border-radius: 12px;
  padding: 16px 18px;
  border: 1px solid var(--grey-300);
  color: inherit;
  transition: all .15s ease;
}
.ch-row:hover {
  border-color: var(--teal-600);
  background: var(--teal-50);
  transform: translateX(2px);
}
.ch-num {
  width: 44px; height: 44px;
  background: var(--teal-100);
  color: var(--teal-700);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 15px;
  flex-shrink: 0;
}
.ch-row:hover .ch-num { background: var(--teal-600); color: white; }
.ch-info { flex: 1; min-width: 0; }
.ch-info .name { font-weight: 600; font-size: 16px; color: var(--ink); }
.ch-info .desc { font-size: 13px; color: var(--slate-500); margin-top: 2px; }
.ch-pages {
  font-size: 13px; color: var(--slate-500);
  flex-shrink: 0; padding-left: 12px;
}

/* ==== Semester dividers ==== */
.sem-block + .sem-block { margin-top: 28px; }
.sem-label {
  display: inline-block;
  font-size: 13px; font-weight: 600;
  padding: 4px 12px;
  background: var(--gold); color: white;
  border-radius: 6px;
  margin-bottom: 12px;
  letter-spacing: 0.5px;
}

/* ==== Chapter viewer ==== */
.viewer-toolbar {
  position: sticky; top: 64px; z-index: 40;
  background: var(--white);
  border-bottom: 1px solid var(--grey-300);
  box-shadow: 0 2px 6px rgba(0,0,0,.04);
}
.viewer-toolbar-inner {
  max-width: 1100px; margin: 0 auto;
  padding: 10px 14px;
  display: flex; align-items: center; gap: 8px;
}
.viewer-toolbar select {
  flex: 1; min-width: 0;
  padding: 9px 10px;
  font-size: 14px;
  border: 1px solid var(--grey-300);
  border-radius: 8px;
  background: white;
  color: var(--ink);
  font-family: inherit;
}
.viewer-toolbar .nav-btn {
  width: 38px; height: 38px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 8px;
  background: var(--teal-600);
  color: white;
  font-weight: 600; font-size: 16px;
  cursor: pointer;
  border: none;
  flex-shrink: 0;
}
.viewer-toolbar .nav-btn:disabled {
  background: var(--grey-300);
  color: var(--grey-500);
  cursor: not-allowed;
}
.viewer-meta {
  background: var(--teal-50);
  padding: 18px 18px 16px;
  border-bottom: 1px solid var(--teal-100);
}
.viewer-meta-inner { max-width: 1100px; margin: 0 auto; }
.viewer-meta .crumbs {
  font-size: 12px; color: var(--slate-500);
  margin-bottom: 6px;
}
.viewer-meta .crumbs a { color: var(--teal-700); }
.viewer-meta h1 {
  font-size: 22px; font-weight: 700; color: var(--ink);
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
}
.viewer-meta h1 .ch-tag {
  background: var(--teal-600); color: white;
  font-size: 13px; font-weight: 600;
  padding: 3px 10px; border-radius: 6px;
}

.pages {
  max-width: 920px; margin: 0 auto;
  padding: 24px 12px 60px;
  display: flex; flex-direction: column; gap: 16px;
}
.page-img {
  width: 100%; height: auto;
  background: white;
  border: 1px solid var(--grey-300);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 4px 12px rgba(0,0,0,.06);
}
.page-img img { width: 100%; display: block; }
.page-no {
  text-align: center;
  font-size: 12px;
  color: var(--slate-500);
  padding: 6px 0 12px;
  border-bottom: 1px dashed var(--grey-300);
}

/* ==== Footer ==== */
.site-footer {
  background: var(--ink);
  color: #C7CDD3;
  padding: 36px 18px 22px;
  margin-top: 60px;
}
.footer-inner {
  max-width: 1100px; margin: 0 auto;
  display: flex; flex-direction: column; gap: 16px;
}
.footer-brand {
  display: flex; align-items: center; gap: 12px;
}
.footer-brand .brand-mark { background: var(--teal-600); }
.footer-brand .brand-name { color: white; }
.footer-brand .brand-tag  { color: #8FA0AC; }
.footer-tagline {
  font-size: 14px; line-height: 1.7;
  max-width: 600px;
}
.footer-meta {
  font-size: 12px;
  color: #8FA0AC;
  display: flex; gap: 14px; flex-wrap: wrap;
  border-top: 1px solid #2A3744;
  padding-top: 16px;
}
.footer-meta a { color: var(--teal-500); }

/* Bottom navigator (in chapter viewer) */
.bottom-nav {
  display: flex; gap: 10px;
  max-width: 920px; margin: 24px auto 0;
  padding: 0 12px;
}
.bottom-nav a {
  flex: 1;
  padding: 14px 16px;
  background: white;
  border: 1px solid var(--grey-300);
  border-radius: 10px;
  font-weight: 600;
  font-size: 14px;
  color: var(--teal-700);
  text-align: center;
}
.bottom-nav a:hover { border-color: var(--teal-600); background: var(--teal-50); }
.bottom-nav a.disabled {
  color: var(--grey-500); pointer-events: none; background: var(--grey-100);
}

/* Top scroll button */
.scroll-top {
  position: fixed; bottom: 22px; right: 22px;
  width: 46px; height: 46px;
  background: var(--teal-600);
  color: white;
  border-radius: 50%;
  border: none;
  display: none; align-items: center; justify-content: center;
  font-size: 18px;
  cursor: pointer;
  box-shadow: 0 6px 18px rgba(42,173,164,0.4);
  z-index: 60;
}
.scroll-top.show { display: flex; }