/* 好好锻炼 —— 家长视角的青少年锻炼指南
   配色与 learn站同源（暖纸 + 宋体），另加草绿作为「身体轴」主色。 */

:root {
  --bg: oklch(0.978 0.012 95);
  --text: oklch(0.38 0.018 70);
  --ink-soft: oklch(0.52 0.016 70);
  --muted: oklch(0.64 0.013 70);
  --line: oklch(0.93 0.010 92);
  --brand: oklch(0.55 0.085 155);
  --brand-soft: oklch(0.95 0.025 155);
  --warn: oklch(0.60 0.100 55);
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  --chip-bg: color-mix(in oklch, var(--brand-soft) 55%, var(--bg));
  --card-bg: color-mix(in oklch, var(--brand-soft) 32%, var(--bg));
  --card-line: color-mix(in oklch, var(--brand) 16%, transparent);
  --serif: "Noto Serif SC", "Songti SC", "STSong", Georgia, serif;
  --sans: "Noto Sans SC", -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --measure: 44em;
  --sidebar-w: 15rem;
  --outline-w: 12rem;
}

*, *::before, *::after { box-sizing: border-box; transition: background-color .25s ease, border-color .25s ease, color .25s ease; }
html { -webkit-font-smoothing: antialiased; scroll-behavior: smooth; }
body { margin: 0; background: var(--bg); color: var(--text); font-family: var(--sans); line-height: 1.78; font-size: 16px; }
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }
:focus-visible { outline: 2px solid var(--brand); outline-offset: 2px; border-radius: 6px; }
::selection { background: var(--brand-soft); color: var(--text); }
.hidden { display: none !important; }

/* ---------- 顶栏 ---------- */
.topbar { position: sticky; top: 0; z-index: 50; display: flex; align-items: center; justify-content: space-between; gap: 16px; padding: 15px 22px; background: color-mix(in oklch, var(--bg) 86%, transparent); backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px); border-bottom: 1px solid var(--line); }
.topbar .brand { font-family: var(--serif); font-weight: 700; font-size: 18px; color: var(--text); display: flex; align-items: center; gap: 9px; }
/* logo 是多细节插画，必须用 background-image 直接显示；
   若用 mask 渲染只会取 alpha，内部线条会糊成一坨实心块。 */
.topbar .brand .brand-icon { width: 20px; height: 24px; flex: 0 0 20px;
  background: url("/logo.svg") center / contain no-repeat; }
.topbar .brand:hover { text-decoration: none; }
.topbar-right { display: flex; align-items: center; gap: 16px; }
.cur-book { color: var(--muted); font-size: 13px; }
.top-link { font-size: 13px; color: var(--ink-soft); border: 1px solid var(--line); padding: 5px 12px; border-radius: 999px; }
.top-link:hover { text-decoration: none; color: var(--brand); border-color: color-mix(in oklch, var(--brand) 45%, transparent); }
.menu-btn { display: none; border: 1px solid var(--line); background: transparent; color: var(--ink-soft); padding: 6px 12px; border-radius: 8px; font: inherit; font-size: 13px; cursor: pointer; }

/* ---------- 布局 ---------- */
.layout { display: flex; align-items: flex-start; }
.sidebar { position: sticky; top: 58px; width: var(--sidebar-w); flex: 0 0 var(--sidebar-w); max-height: calc(100vh - 58px); overflow-y: auto; padding: 22px 16px 40px; border-right: 1px solid var(--line); }
.content { flex: 1 1 auto; min-width: 0; padding: 4vh 36px 16vh; }
.scrim { display: none; }

.outline { position: sticky; top: 58px; align-self: flex-start; width: var(--outline-w); flex: 0 0 var(--outline-w); max-height: calc(100vh - 58px); overflow-y: auto; padding: 26px 14px 40px; }
.outline-title { font-size: 11px; letter-spacing: 2px; color: var(--muted); margin-bottom: 12px; font-weight: 600; }
#outline-nav a { display: block; font-size: 13px; line-height: 1.55; color: var(--muted); padding: 4px 0 4px 12px; margin-left: -1px; border-left: 1px solid var(--line); }
#outline-nav a.lvl-h3 { padding-left: 24px; font-size: 12.5px; }
#outline-nav a.lvl-act { padding-left: 24px; font-size: 12.5px; color: var(--muted); }
#outline-nav a.lvl-act.act-hard { color: color-mix(in oklch, var(--warn) 70%, var(--muted)); }
#outline-nav a.lvl-act.active { color: var(--brand); }
#outline-nav a:hover { color: var(--brand); text-decoration: none; }
#outline-nav a.active { color: var(--brand); font-weight: 600; border-left-color: var(--brand); }

/* ---------- 侧栏树 ---------- */
.tree .strand { margin-bottom: 22px; }
.tree .strand-title { font-size: 11px; letter-spacing: 2px; color: var(--muted); font-weight: 600; margin-bottom: 8px; padding-left: 2px; }
.tree .strand.active .strand-title { color: var(--brand); }
.tree .stage-title { font-size: 12px; color: var(--ink-soft); margin: 12px 0 4px; padding-left: 12px; font-weight: 700; }
.tree a.lesson-link { display: block; font-size: 13.5px; color: var(--ink-soft); padding: 5px 0 5px 12px; border-left: 2px solid transparent; }
.tree a.lesson-link:hover { color: var(--brand); text-decoration: none; }
.tree a.lesson-link.active { color: var(--brand); font-weight: 700; border-left-color: var(--brand); }

/* ---------- 书架（首页） ---------- */
.bookshelf { width: 100%; max-width: 52rem; margin: 0 auto; }

/* ---------- 首页：gitbook 式平铺目录 ---------- */
.bookshelf { width: 100%; max-width: 46rem; margin: 0 auto; }
.gh-head { margin-bottom: 3rem; }
.gh-head h1 { font-family: var(--serif); font-size: clamp(26px, 4vw, 34px); font-weight: 700; margin: 0 0 8px; }
.gh-sub { font-size: 15px; color: var(--ink-soft); margin: 0 0 4px; }
.gh-aud { font-size: 13px; color: var(--muted); margin: 0; }

.toc-strand { margin-bottom: 2.6rem; }
.toc-strand > h2 { font-family: var(--serif); font-size: 18px; font-weight: 700;
  margin: 0 0 4px; padding-bottom: 8px; border-bottom: 1px solid var(--line);
  display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; }
.toc-sub { font-family: var(--sans); font-size: 12.5px; font-weight: 400; color: var(--muted); }
.toc-empty { font-size: 13.5px; color: var(--muted); margin: 10px 0 0; }

.toc-book { margin: 18px 0 0; }
.toc-book h3 { margin: 0; font-size: 15.5px; font-weight: 700; }
.toc-book h3 a { color: var(--text); }
.toc-book h3 a:hover { color: var(--brand); text-decoration: none; }
.toc-bsub { font-size: 13px; color: var(--muted); margin: 3px 0 0; }
.toc-book ul { list-style: none; margin: 7px 0 0; padding: 0; }
.toc-book li { margin: 0; }
.toc-book li a { display: block; font-size: 14.5px; color: var(--ink-soft);
  padding: 5px 0 5px 14px; border-left: 2px solid transparent; }
.toc-book li a:hover { color: var(--brand); text-decoration: none; border-left-color: var(--brand); }

.empty-box { color: var(--muted); font-size: 14px; padding: 18px 0; }

/* ---------- 课文 ---------- */
.lesson { width: 100%; max-width: var(--measure); margin: 0 auto; }
.crumb { font-size: 12.5px; color: var(--muted); margin-bottom: 14px; }
.crumb a { color: var(--muted); }
.crumb .sep { margin: 0 7px; color: var(--line); }
.crumb .now { color: var(--ink-soft); }
.lesson h1 { font-family: var(--serif); font-size: clamp(26px, 3.6vw, 34px); font-weight: 700; line-height: 1.4; margin: 0 0 6px; }
.lesson-body { font-size: 16.5px; }
.lesson-body h2 { font-family: var(--serif); font-size: 22px; font-weight: 700; margin: 2.6em 0 .7em; padding-top: .3em; letter-spacing: .3px; }
.lesson-body h3 { font-size: 17.5px; font-weight: 700; margin: 2em 0 .5em; }
.lesson-body p { margin: 1.05em 0; }
.lesson-body ul, .lesson-body ol { padding-left: 1.5em; margin: 1em 0; }
.lesson-body li { margin: .4em 0; }
.lesson-body strong { font-weight: 700; }
.lesson-body hr { border: 0; border-top: 1px solid var(--line); margin: 2.6em 0; }
.lesson-body table { width: 100%; border-collapse: collapse; margin: 1.3em 0; font-size: 14.5px; }
.lesson-body th, .lesson-body td { text-align: left; padding: 9px 12px; border-bottom: 1px solid var(--line); }
.lesson-body th { background: color-mix(in oklch, var(--brand-soft) 34%, var(--bg)); font-weight: 700; }

blockquote { margin: 1.4em 0; padding: 14px 18px; border-left: 3px solid color-mix(in oklch, var(--brand) 45%, transparent); background: var(--card-bg); border-radius: 0 12px 12px 0; }
blockquote p { margin: .6em 0; }

/* 证据标记 */
.ev { display: inline-block; font-size: 11.5px; font-weight: 700; letter-spacing: .4px; padding: 1px 8px; border-radius: 999px; vertical-align: 2px; margin-right: 4px; white-space: nowrap; }
.ev-a { background: color-mix(in oklch, 0.72 0.10 155 22%, var(--bg)); color: oklch(0.46 0.09 155); }
.ev-b { background: color-mix(in oklch, 0.70 0.09 225 20%, var(--bg)); color: oklch(0.46 0.08 225); }
.ev-c { background: color-mix(in oklch, 0.75 0.09 70 22%, var(--bg)); color: oklch(0.50 0.08 70); }
.ev-d { background: color-mix(in oklch, 0.65 0.11 40 20%, var(--bg)); color: oklch(0.50 0.10 40); }


/* ---------- 动作卡片 ---------- */
.act { margin: 1.7em 0; border: 1px solid var(--card-line); border-radius: 14px; background: color-mix(in oklch, var(--card-bg) 55%, var(--bg)); overflow: hidden; }
.act-h { font-family: var(--serif); font-weight: 700; font-size: 17px; padding: 14px 18px; border-bottom: 1px solid var(--card-line); background: color-mix(in oklch, var(--brand-soft) 40%, var(--bg)); }
.act-h .act-idx { color: var(--muted); font-family: var(--sans); font-size: 12px; font-weight: 400; margin-left: 8px; }
.act-b { padding: 4px 18px 16px; }
.act-b p { margin: .85em 0; font-size: 15.5px; line-height: 1.75; }
.act-b strong { color: var(--brand); font-weight: 700; margin-right: 2px; }

/* 动作库筛选 */
.lib-filters { display: flex; flex-wrap: wrap; gap: 10px; margin: 22px 0 10px; }
.lib-group { font-size: 11px; letter-spacing: 1.5px; color: var(--muted); font-weight: 600; margin: 26px 0 8px; }
.lib-item { display: block; color: inherit; text-decoration: none; padding: 15px 18px; border: 1px solid var(--line); border-radius: 12px; margin-bottom: 10px; background: color-mix(in oklch, var(--card-bg) 30%, var(--bg)); }
.lib-item:hover { text-decoration: none; border-color: color-mix(in oklch, var(--brand) 35%, transparent); }
.lib-item .name { font-family: var(--serif); font-weight: 700; font-size: 17px; }
.lib-item .meta { font-size: 12.5px; color: var(--muted); margin-top: 5px; }
.lib-item .chips { margin-top: 8px; display: flex; flex-wrap: wrap; gap: 6px; }
.chip { font-size: 11.5px; padding: 2px 9px; border-radius: 999px; background: var(--chip-bg); color: oklch(0.46 0.07 155); }
.chip-lv { background: color-mix(in oklch, 0.75 0.09 70 20%, var(--bg)); color: oklch(0.50 0.08 70); }

/* 上下篇 */
.lesson-nav { display: flex; gap: 16px; margin-top: 4em; padding-top: 24px; border-top: 1px solid var(--line); }
.ln-item { flex: 1; display: block; color: inherit; text-decoration: none; padding: 14px 18px; border: 1px solid var(--line); border-radius: 12px; }
.ln-item:hover { text-decoration: none; border-color: color-mix(in oklch, var(--brand) 35%, transparent); }
.ln-item.disabled { visibility: hidden; }
.ln-label { display: block; font-size: 11px; letter-spacing: 1.5px; color: var(--muted); margin-bottom: 4px; }
.ln-title { font-family: var(--serif); font-weight: 700; font-size: 16px; }
.pos-theme { font-size: 14px; color: var(--ink-soft); font-style: italic; margin: 0 0 1.4em; padding-left: 12px; border-left: 2px solid var(--line); }

/* ---------- 移动端 ---------- */
@media (max-width: 860px) {
  .sidebar { position: fixed; top: 0; left: 0; bottom: 0; z-index: 60; background: var(--bg); transform: translateX(-100%); transition: transform .22s ease; max-height: none; padding-top: 70px; }
  .sidebar.open { transform: none; }
  .scrim { display: block; position: fixed; inset: 0; background: rgba(30,35,32,.3); opacity: 0; pointer-events: none; transition: opacity .22s ease; z-index: 55; }
  .scrim.show { opacity: 1; pointer-events: auto; }
  .menu-btn { display: inline-block; }
  .outline { display: none; }
  .content { padding: 3vh 20px 14vh; }
  .cur-book { display: none; }
  .lesson-body { font-size: 16px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}
@media print {
  .topbar, .sidebar, .outline, .scrim, .lesson-nav, .crumb { display: none !important; }
  .content { padding: 0; }
  .act { break-inside: avoid; }
}