:root {
  --ink: #0f172a;
  --muted: #64748b;
  --line: #e2e8f0;
  --paper: #ffffff;
  --wash: #f8fafc;
  --accent: #2563eb;
  --accent-soft: #eff6ff;
  --shadow: 0 18px 45px rgba(15, 23, 42, .08);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
.sidebar { position: sticky; top: 0; height: 100vh; overflow: auto; }
.chapter-link {display:block;padding:7px 10px;color:var(--muted);font-size:13px;line-height:1.5;text-decoration:none;}
.chapter-link:hover {background:var(--accent-soft);color:var(--accent);}
.level-2 {padding-left:20px;}.level-3 {padding-left:30px;}
.content-block {scroll-margin-top:24px;}
.content-block.callout {background:#fff6eb;border:1px solid #ffd1a3;padding:16px 22px;border-radius:8px;margin:12px 0;}
.content-block h1,.content-block h2,.content-block h3 {font-size:24px;line-height:1.5;margin:20px 0 8px;}
@media(max-width:760px){.sidebar{position:relative;height:auto;max-height:48vh;}}
body { margin: 0; color: var(--ink); background: var(--wash); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; }
button, input { font: inherit; }
.topbar { min-height: 82px; display: flex; align-items: center; gap: 14px; padding: 17px 34px; background: var(--paper); border-bottom: 1px solid var(--line); }
.brand-mark { width: 40px; height: 40px; display: grid; place-items: center; background: var(--ink); color: white; font-weight: 800; letter-spacing: .04em; }
.eyebrow { margin: 0 0 2px; color: var(--accent); font-size: 10px; font-weight: 800; letter-spacing: .14em; }
h1 { margin: 0; font-size: 21px; letter-spacing: .01em; }
.top-meta { margin-left: auto; color: var(--muted); font-size: 13px; }
.shell { display: grid; grid-template-columns: 300px minmax(0, 1fr); min-height: calc(100vh - 82px); }
.sidebar { padding: 24px 18px; border-right: 1px solid var(--line); background: #fbfdff; }
.search-box { display: flex; align-items: center; gap: 8px; padding: 10px 12px; border: 1px solid var(--line); background: white; border-radius: 8px; color: var(--muted); }
.search-box input { width: 100%; border: 0; outline: 0; color: var(--ink); background: transparent; font-size: 14px; }
.side-heading { display: flex; justify-content: space-between; margin: 26px 6px 10px; color: var(--muted); font-size: 12px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; }
.page-list { display: grid; gap: 5px; }
.page-item { width: 100%; padding: 12px 12px; border: 1px solid transparent; border-radius: 7px; background: transparent; color: var(--ink); text-align: left; cursor: pointer; line-height: 1.45; font-size: 14px; }
.page-item:hover { background: var(--accent-soft); }
.page-item.active { border-color: #bfdbfe; background: var(--accent-soft); color: #1d4ed8; font-weight: 700; }
.side-note { margin: 28px 6px 0; color: var(--muted); font-size: 12px; line-height: 1.7; }
.reader { min-width: 0; padding: 32px clamp(22px, 5vw, 80px) 80px; }
.empty-state { display: grid; place-items: center; min-height: 50vh; color: var(--muted); font-size: 16px; }
.article { max-width: 940px; margin: 0 auto; }
.article-toolbar { display: flex; justify-content: space-between; align-items: center; gap: 12px; color: var(--muted); font-size: 13px; }
.source-link { color: var(--accent); text-decoration: none; font-weight: 600; }
.source-link:hover { text-decoration: underline; }
h2 { margin: 16px 0 24px; font-size: clamp(28px, 4vw, 42px); line-height: 1.16; letter-spacing: -.02em; }
.article-text { padding: 28px 0; border-top: 1px solid var(--line); white-space: pre-wrap; font-size: 16px; line-height: 1.9; }
.content-block { padding: 12px 0; white-space: pre-wrap; }
.inline-media { max-width: 760px; margin: 14px 0; }
.media-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 14px; margin: 0 0 26px; }
.media-card { margin: 0; border: 1px solid var(--line); background: white; border-radius: 8px; overflow: hidden; box-shadow: var(--shadow); }
.media-card img, .media-card video { display: block; width: 100%; max-height: 520px; object-fit: contain; background: #0f172a; }
.article img { cursor: zoom-in; }
.article img:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }
.image-viewer { position: fixed; inset: 0; width: 100vw; height: 100dvh; max-width: none; max-height: none; margin: 0; padding: 56px 72px 32px; border: 0; background: rgba(8, 12, 20, .94); color: #fff; overflow: hidden; }
.image-viewer::backdrop { background: rgba(8, 12, 20, .88); }
.viewer-figure { width: 100%; height: 100%; margin: 0; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 12px; }
.viewer-figure img { display: block; width: 100%; height: calc(100% - 34px); object-fit: contain; }
.viewer-figure figcaption { min-height: 22px; max-width: 90%; color: rgba(255,255,255,.82); text-align: center; font-size: 13px; }
.viewer-close, .viewer-step { position: absolute; z-index: 1; display: grid; place-items: center; width: 44px; height: 44px; padding: 0; border: 1px solid rgba(255,255,255,.32); border-radius: 50%; color: #fff; background: rgba(255,255,255,.12); cursor: pointer; }
.viewer-close { top: 16px; right: 20px; font-size: 29px; line-height: 1; }
.viewer-step { top: 50%; transform: translateY(-50%); font-size: 36px; line-height: 1; }
.viewer-step.previous { left: 18px; }.viewer-step.next { right: 18px; }
.viewer-close:hover, .viewer-step:hover { background: rgba(255,255,255,.25); }
.viewer-close:focus-visible, .viewer-step:focus-visible { outline: 3px solid #93c5fd; outline-offset: 3px; }
@media (max-width: 600px) { .image-viewer { padding: 58px 48px 24px; }.viewer-step.previous { left: 6px; }.viewer-step.next { right: 6px; }.viewer-close { top: 8px; right: 8px; } }
.media-card figcaption { padding: 9px 12px; color: var(--muted); font-size: 12px; }
.related { padding-top: 26px; border-top: 1px solid var(--line); }
.related h3 { margin: 0 0 12px; font-size: 16px; }
.related-link { display: block; padding: 9px 0; color: var(--accent); text-decoration: none; font-size: 14px; }
.related-link:hover { text-decoration: underline; }
@media (max-width: 760px) {
  .topbar { padding: 15px 18px; }
  .top-meta { display: none; }
  .shell { display: block; }
  .sidebar { border-right: 0; border-bottom: 1px solid var(--line); }
  .page-list { grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }
  .reader { padding: 24px 18px 60px; }
}
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; transition: none !important; } }