/* ==========================================================================
   数字教材 · 阅读壳（shell.css）
   目录 / 章扉页 / 阅读区 / 顶栏。与书无关，只与版式有关。
   ========================================================================== */

* { margin: 0; padding: 0; }

:root {
  --ink: #1f2320;
  --ink-2: #4a524c;
  --ink-3: #8b938c;
  --paper: #fbfaf6;
  --paper-2: #f4f1e8;
  --rule: #dcd8cc;
  --brand: #2f6f4f;
  --gold: #a8813f;
  --serif: "Songti SC", "Source Han Serif SC", "Noto Serif SC", Georgia, serif;
  --sans: -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --toc-w: 288px;
  --top-h: 56px;
}

html { scroll-behavior: smooth; }

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  -webkit-font-smoothing: antialiased;
}

/* ---------------------------------------------------------------- 顶栏 */
.top {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--top-h);
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 0 22px;
  background: rgba(251, 250, 246, .92);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--rule);
}
.top .brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--serif);
  font-size: 15px;
  letter-spacing: .06em;
  color: var(--ink);
}
.top .brand i {
  width: 18px; height: 18px;
  border-radius: 3px;
  background: var(--brand);
  display: inline-block;
  position: relative;
}
.top .brand i::after {
  content: "";
  position: absolute;
  left: 5px; top: 4px;
  width: 2px; height: 10px;
  background: #fff;
  box-shadow: 4px 0 0 #fff;
  opacity: .8;
}
.top .bookname {
  font-size: 13px;
  color: var(--ink-3);
  padding-left: 14px;
  border-left: 1px solid var(--rule);
}
.top .spacer { flex: 1; }
.top .stat {
  font-size: 12px;
  color: var(--ink-3);
  font-variant-numeric: tabular-nums;
}
.top .switcher {
  display: flex;
  gap: 2px;
  padding: 3px;
  background: var(--paper-2);
  border-radius: 7px;
}
.top .switcher a {
  padding: 4px 12px;
  border-radius: 5px;
  font-size: 12.5px;
  color: var(--ink-2);
  text-decoration: none;
}
.top .switcher a.on {
  background: #fff;
  color: var(--brand);
  box-shadow: 0 1px 2px rgba(0, 0, 0, .06);
}

/* ---------------------------------------------------------------- 布局 */
.shell {
  display: flex;
  align-items: flex-start;
}
/* hidden 属性会被上面的 display:flex 盖掉，闸门页就会被推到一屏之外 */
.shell[hidden] { display: none; }

.toc {
  position: sticky;
  top: var(--top-h);
  width: var(--toc-w);
  height: calc(100vh - var(--top-h));
  overflow-y: auto;
  padding: 26px 12px 60px 26px;
  border-right: 1px solid var(--rule);
  background: linear-gradient(90deg, #f6f3ea 0%, var(--paper) 100%);
}
.toc::-webkit-scrollbar { width: 6px; }
.toc::-webkit-scrollbar-thumb { background: #d8d3c4; border-radius: 3px; }

.toc .toc-h {
  font-size: 11px;
  letter-spacing: .22em;
  color: var(--ink-3);
  margin-bottom: 14px;
}

.toc a {
  display: flex;
  align-items: baseline;
  gap: 9px;
  padding: 7px 10px 7px 8px;
  border-radius: 6px;
  color: var(--ink-2);
  text-decoration: none;
  font-size: 13.5px;
  line-height: 1.5;
  border-left: 2px solid transparent;
  transition: background .16s, color .16s, border-color .16s;
}
.toc a:hover { background: rgba(47, 111, 79, .06); color: var(--ink); }
.toc a.on {
  background: rgba(47, 111, 79, .09);
  color: var(--brand);
  border-left-color: var(--brand);
  font-weight: 500;
}
.toc .toc-l1 { margin-top: 2px; font-family: var(--serif); font-size: 15px; color: var(--ink); }
.toc .toc-no {
  font-family: var(--sans);
  font-size: 10.5px;
  color: var(--ink-3);
  font-variant-numeric: tabular-nums;
  letter-spacing: .02em;
  min-width: 15px;
}
.toc a.on .toc-no { color: var(--brand); }
.toc .toc-tx { flex: 1; }

.toc .toc-sub {
  margin: 1px 0 8px 0;
  padding-left: 8px;
  border-left: 1px dashed #ddd8c9;
}
.toc .toc-sub a { font-size: 12.5px; padding: 4px 8px; color: #5f665f; }
.toc .toc-l3 { padding-left: 20px; font-size: 12px; color: #757c74; }

/* ---------------------------------------------------------------- 阅读区 */
.main {
  flex: 1;
  min-width: 0;
  padding: 0 0 30vh;
}
.doc {
  max-width: 752px;
  margin: 0 auto;
  padding: 0 40px;
}

/* 章扉页 */
.uc {
  min-height: calc(100vh - var(--top-h));
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
  position: relative;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 3.4em;
}
.uc::after {
  content: "";
  position: absolute;
  left: -40px;
  top: 50%;
  width: 3px;
  height: 96px;
  transform: translateY(-50%);
  background: linear-gradient(180deg, transparent, var(--brand), transparent);
  opacity: .35;
}
.uc-no {
  font-family: var(--serif);
  font-size: 13px;
  letter-spacing: .34em;
  color: var(--gold);
  text-transform: uppercase;
  margin-bottom: 22px;
}
.uc-title {
  font-family: var(--serif);
  font-size: 46px;
  line-height: 1.28;
  font-weight: 400;
  letter-spacing: .03em;
  color: var(--ink);
  margin: 0 0 18px;
  max-width: 12em;
}
.uc-sub {
  font-family: var(--sans);
  font-size: 14px;
  color: var(--ink-3);
  letter-spacing: .12em;
  margin-bottom: 30px;
}
.uc-rule {
  width: 64px;
  height: 2px;
  background: var(--gold);
  margin-bottom: 26px;
}
.flat .uc { min-height: auto; padding: 64px 0 52px; }
.flat .uc::after { display: none; }

.uc-meta {
  font-family: var(--sans);
  font-size: 12px;
  color: var(--ink-3);
  letter-spacing: .1em;
  font-variant-numeric: tabular-nums;
}

.dtb-chapter.is-long { content-visibility: auto; contain-intrinsic-size: auto 2400px; }

/* 篇章之间 */
.dtb-chapter + .dtb-chapter { margin-top: 4em; }

/* 首章去掉顶部留白 */
.dtb-chapter:first-child .uc { margin-top: -8px; }

/* ---------------------------------------------------------------- 响应式 */
@media (max-width: 1080px) {
  :root { --toc-w: 240px; }
  .uc-title { font-size: 38px; }
  .doc { padding: 0 26px; }
}
@media (max-width: 820px) {
  .toc { display: none; }
  .uc-title { font-size: 30px; }
  .doc { padding: 0 20px; }
  .top .bookname { display: none; }
}

/* ---------------------------------------------------------------- 发布状态条 */
.pubbar {
  position: sticky;
  top: var(--top-h);
  z-index: 45;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 22px;
  font-size: 12.5px;
  color: #6b5320;
  background: #fdf6e3;
  border-bottom: 1px solid #ecdcb4;
}
.pubbar b { font-weight: 600; letter-spacing: .04em; }
.pubbar span { color: #8a7440; font-variant-numeric: tabular-nums; }
.pubbar .pubbar-note { margin-left: auto; color: #a08a55; }
.pubbar.is-off { background: #fbeeee; border-bottom-color: #eed4d4; color: #8a3b3b; }
.pubbar.is-off span { color: #a56a6a; }

/* ---------------------------------------------------------------- 修订标记 */
.dtb [data-rev] { position: relative; }
.dtb [data-rev]::after {
  content: "";
  position: absolute;
  left: -14px;
  top: .35em;
  bottom: .35em;
  width: 2px;
  border-radius: 2px;
  background: var(--gold);
  opacity: .55;
}
.dtb [data-rev]:hover::after { opacity: 1; }

/* ---------------------------------------------------------------- 下线拦截 */
.gate-screen {
  min-height: calc(100vh - var(--top-h));
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px 20px;
  background: var(--paper);
}
.gate-screen[hidden] { display: none; }
.gate-card {
  max-width: 420px;
  text-align: center;
  padding: 44px 36px;
  background: #fff;
  border: 1px solid var(--rule);
  border-radius: 10px;
  box-shadow: 0 18px 48px rgba(40, 44, 40, .07);
}
.gate-k {
  font-family: var(--serif);
  font-size: 44px;
  line-height: 1;
  color: var(--rule);
  letter-spacing: .08em;
}
.gate-card h2 {
  font-family: var(--serif);
  font-size: 22px;
  font-weight: 600;
  margin: 14px 0 10px;
}
.gate-card p { font-size: 14px; line-height: 1.8; color: var(--ink-2); }
.gate-card .gate-sub { font-size: 12px; color: var(--ink-3); margin-top: 6px; font-variant-numeric: tabular-nums; }
.gate-btn {
  display: inline-block;
  margin-top: 22px;
  padding: 9px 20px;
  border-radius: 999px;
  background: var(--brand);
  color: #fff;
  font-size: 13px;
  text-decoration: none;
}