/* Layout: 顶部细导航条（路线 / 笔记 / 代码），路线页是阶段轨 + 单阶段展开，笔记页是左侧目录 + 居中正文（约 68 字宽） */
:root {
  --bg: #F3F5F6;
  --surface: #FFFFFF;
  --ink: #17212B;
  --muted: #5A6874;
  --line: #D9E0E5;
  --accent: #1D5C8A;
  --accent-soft: #E1ECF5;
  --done: #2F7D4F;
  --done-soft: #E2F1E7;
  --warn: #9A5B00;
  --warn-soft: #FBEFD9;
  --code-bg: #EAEFF2;
  --pre-bg: #1B242C;
  --pre-ink: #DCE5EC;
  --display: "Noto Serif SC", "Songti SC", serif;
  --body: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #11171C; --surface: #182129; --ink: #E4EAEF; --muted: #93A2AE; --line: #2A3641;
    --accent: #7DB6E3; --accent-soft: #1C3346; --done: #6CC28F; --done-soft: #1B3326;
    --warn: #E6B567; --warn-soft: #3A2D16; --code-bg: #1F2A33; --pre-bg: #0B1014; --pre-ink: #D3DDE5;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #11171C; --surface: #182129; --ink: #E4EAEF; --muted: #93A2AE; --line: #2A3641;
  --accent: #7DB6E3; --accent-soft: #1C3346; --done: #6CC28F; --done-soft: #1B3326;
  --warn: #E6B567; --warn-soft: #3A2D16; --code-bg: #1F2A33; --pre-bg: #0B1014; --pre-ink: #D3DDE5;
  color-scheme: dark;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font-family: var(--body); font-size: 16px; line-height: 1.75; }
a { color: var(--accent); text-underline-offset: 3px; }
a:focus-visible, button:focus-visible, input:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
code { font-family: var(--mono); font-size: .88em; background: var(--code-bg); padding: 1px 5px; border-radius: 3px; overflow-wrap: anywhere; }

/* 顶部导航 */
.topbar { position: sticky; top: 0; z-index: 10; background: var(--surface); border-bottom: 1px solid var(--line); }
.topbar-in { max-width: 1120px; margin: 0 auto; display: flex; align-items: center; gap: 20px; padding: 10px max(16px, env(safe-area-inset-left, 0px)) 10px max(16px, env(safe-area-inset-right, 0px)); flex-wrap: wrap; }
.brand { font-family: var(--mono); font-weight: 600; font-size: 14px; color: var(--ink); text-decoration: none; letter-spacing: .02em; }
.brand span { color: var(--accent); }
.topnav { display: flex; gap: 4px; margin-left: auto; flex-wrap: wrap; }
.topnav a { text-decoration: none; color: var(--muted); font-size: 14px; padding: 4px 10px; border-radius: 4px; }
.topnav a:hover { color: var(--ink); background: var(--code-bg); }
.topnav a[aria-current="page"] { color: var(--accent); background: var(--accent-soft); font-weight: 500; }

.page { max-width: 1120px; margin: 0 auto; padding: 32px max(16px, env(safe-area-inset-right, 0px)) 72px max(16px, env(safe-area-inset-left, 0px)); }
.eyebrow { font-family: var(--mono); font-size: 12px; letter-spacing: .08em; color: var(--muted); }
h1 { font-family: var(--display); font-weight: 900; font-size: clamp(28px, 5vw, 40px); line-height: 1.25; margin: 0; text-wrap: balance; }
.lead { color: var(--muted); max-width: 64ch; margin: 0; }

/* 笔记阅读页 */
.reader { display: grid; grid-template-columns: 240px minmax(0, 1fr); gap: 48px; align-items: start; }
.toc { order: -1; position: sticky; top: 72px; max-height: calc(100vh - 96px); overflow: auto; font-size: 14px; display: grid; gap: 18px; padding-right: 4px; }
.toc h4 { margin: 0 0 4px; font-family: var(--mono); font-size: 12px; letter-spacing: .08em; color: var(--muted); font-weight: 600; }
.toc ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 2px; }
.toc a { display: block; padding: 3px 10px; border-left: 2px solid transparent; color: var(--muted); text-decoration: none; line-height: 1.5; }
.toc a:hover { color: var(--ink); }
.toc a[aria-current="page"] { color: var(--accent); border-left-color: var(--accent); font-weight: 500; }
@media (max-width: 860px) {
  .reader { grid-template-columns: minmax(0, 1fr); gap: 24px; }
  .toc { position: static; max-height: none; order: 2; border-top: 1px solid var(--line); padding-top: 20px; }
}
article { max-width: 68ch; min-width: 0; }
article header { display: grid; gap: 10px; margin-bottom: 28px; }
article .meta { display: flex; flex-wrap: wrap; gap: 8px; font-size: 13px; }
.chip { font-family: var(--mono); background: var(--code-bg); padding: 2px 8px; border-radius: 4px; color: var(--muted); }
.chip.stage { background: var(--accent-soft); color: var(--accent); }
.prose h2 { font-family: var(--display); font-size: 23px; line-height: 1.35; margin: 40px 0 12px; text-wrap: balance; }
.prose h3 { font-size: 17px; margin: 28px 0 8px; }
.prose p, .prose ul, .prose ol { margin: 0 0 14px; }
.prose ul, .prose ol { padding-left: 1.4em; }
.prose li { margin-bottom: 4px; }
.prose pre { background: var(--pre-bg); color: var(--pre-ink); padding: 14px 16px; border-radius: 6px; overflow-x: auto; font-size: 13.5px; line-height: 1.6; margin: 0 0 18px; position: relative; }
.prose pre code { background: none; padding: 0; color: inherit; font-size: inherit; overflow-wrap: normal; }
.prose table { border-collapse: collapse; width: 100%; font-size: 14.5px; margin: 0 0 18px; display: block; overflow-x: auto; }
.prose th, .prose td { border: 1px solid var(--line); padding: 7px 10px; text-align: left; vertical-align: top; }
.prose th { background: var(--code-bg); font-weight: 600; white-space: nowrap; }
.prose blockquote { margin: 0 0 18px; padding: 10px 16px; border-left: 3px solid var(--accent); background: var(--accent-soft); border-radius: 0 6px 6px 0; }
.prose blockquote p:last-child { margin: 0; }
.prose hr { border: 0; border-top: 1px solid var(--line); margin: 32px 0; }
.copy { position: absolute; top: 8px; right: 8px; font: 12px var(--mono); padding: 2px 8px; border-radius: 4px; border: 1px solid #3A4A57; background: transparent; color: var(--pre-ink); cursor: pointer; opacity: .75; }
.copy:hover { opacity: 1; }
details.quiz { border: 1px solid var(--line); background: var(--surface); border-radius: 6px; padding: 10px 14px; margin: 0 0 8px; }
details.quiz summary { cursor: pointer; font-weight: 500; }
details.quiz[open] summary { margin-bottom: 6px; }
.pager { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 12px; margin-top: 48px; }
.pager a { display: grid; gap: 2px; padding: 12px 14px; border: 1px solid var(--line); border-radius: 6px; background: var(--surface); text-decoration: none; color: var(--ink); min-width: 0; }
.pager a:hover { border-color: var(--accent); }
.pager small { color: var(--muted); font-size: 12px; font-family: var(--mono); }
.pager .next { text-align: right; grid-column: 2; }
.sources { font-size: 14px; color: var(--muted); }

/* 笔记目录页 */
.stage-group { display: grid; gap: 12px; margin-top: 36px; }
.stage-group h2 { font-family: var(--display); font-size: 22px; margin: 0; }
.stage-group .when { font-size: 13px; color: var(--muted); }
.note-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 10px; }
.note-card { display: grid; gap: 4px; align-content: start; padding: 14px 16px; background: var(--surface); border: 1px solid var(--line); border-radius: 6px; text-decoration: none; color: var(--ink); min-width: 0; }
.note-card:hover { border-color: var(--accent); }
.note-card strong { font-size: 16px; }
.note-card span { color: var(--muted); font-size: 14px; line-height: 1.6; }
.note-card .read { font-family: var(--mono); font-size: 12px; color: var(--accent); }
.note-card.pending { opacity: .55; pointer-events: none; border-style: dashed; }

footer.site { max-width: 1120px; margin: 0 auto; padding: 20px max(16px, env(safe-area-inset-right, 0px)) 40px max(16px, env(safe-area-inset-left, 0px)); font-size: 13px; color: var(--muted); border-top: 1px solid var(--line); }
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }
.license-note { font-size: 14px; line-height: 1.65; background: var(--warn-soft); color: var(--ink); border-radius: 6px; padding: 10px 14px; margin: 0 0 24px; }
.license-note a { overflow-wrap: anywhere; }
.license-note strong { display: block; color: var(--warn); font-size: 12px; font-family: var(--mono); letter-spacing: .08em; margin-bottom: 2px; }
.prose p.from { color: var(--muted); font-size: 14px; margin: -6px 0 12px; }
details.quiz strong:first-child { color: var(--accent); }
.prose p.codefile { margin: 0 0 6px; font-size: 13px; color: var(--muted); display: flex; gap: 10px; align-items: baseline; }
.prose p.codefile + pre { margin-top: 0; }
.prose li.check { list-style: none; margin-left: -1.4em; display: flex; gap: 8px; align-items: baseline; }
.prose li.check input { accent-color: var(--done); width: 15px; height: 15px; flex: none; transform: translateY(2px); }
.stage-group h3.kind { font-size: 14px; font-family: var(--mono); letter-spacing: .06em; color: var(--muted); margin: 6px 0 0; font-weight: 600; }
details.codeview summary { display: flex; gap: 10px; align-items: baseline; }
details.codeview .lines { color: var(--muted); font-size: 13px; font-weight: 400; }
details.codeview pre { margin-top: 8px; }