/* MetaUSI v2 —— 纸上编辑部 (paper editorial) */
:root{
  --paper:#f6f5f1;
  --ink:#1c1b18;
  --muted:#6f6c66;
  --accent:#244bff;
  --line:rgba(0,0,0,.12);
  --surface:#efeee9;
  --serif:Georgia,"Songti SC","STSong","Noto Serif SC","SimSun",serif;
  --sans:system-ui,-apple-system,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --mono:ui-monospace,"SF Mono",Menlo,Consolas,monospace;
  color-scheme:light;
}
[data-theme="dark"]{
  --paper:#141412;
  --ink:#e8e6e1;
  --muted:#a3a099;
  --accent:#8ba0ff;
  --line:rgba(255,255,255,.14);
  --surface:#1d1d1a;
  color-scheme:dark;
}

/* base */
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:24px}
body{
  margin:0;background:var(--paper);color:var(--ink);
  font:1.125rem/2 var(--sans);
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
}
img{display:block;max-width:100%;height:auto}
h1,h2,h3,p,ol,ul,figure{margin:0}
ol,ul{padding:0;list-style:none}
a{color:inherit;text-decoration:none}
a:hover{color:var(--accent)}
a:focus-visible,button:focus-visible{outline:2px solid var(--accent);outline-offset:4px;border-radius:2px}
::selection{background:var(--accent);color:var(--paper)}
p{text-wrap:pretty}
.mono{font-family:var(--mono);font-variant-numeric:tabular-nums}

.container{width:min(880px,calc(100% - 48px));margin-inline:auto}
.narrow{max-width:700px}

.skip-link{position:fixed;top:0;left:20px;transform:translateY(-160%);z-index:60;
  background:var(--accent);color:#fff;padding:10px 20px;font-size:.9rem;border-radius:0 0 6px 6px}
.skip-link:focus{transform:translateY(0);color:#fff}

/* kickers */
.kicker{font-family:var(--mono);font-size:.75rem;letter-spacing:.14em;color:var(--muted);text-transform:uppercase}

/* masthead */
.masthead{border-bottom:1px solid var(--line)}
.masthead-inner{display:flex;align-items:center;justify-content:space-between;height:76px;gap:16px}
.wordmark{font-family:var(--serif);font-size:1.45rem;font-weight:700;letter-spacing:-.02em}
.wordmark:hover{color:var(--ink)}
.site-nav{display:flex;align-items:center;gap:26px;font-size:.95rem}
.site-nav a{padding:6px 0;color:var(--ink)}
.site-nav a[aria-current="page"]{color:var(--accent);font-weight:600}
.nav-icons{display:flex;align-items:center;gap:6px;margin-left:6px;padding-left:14px;border-left:1px solid var(--line)}
.icon-btn{display:inline-flex;align-items:center;justify-content:center;width:36px;height:36px;
  border:1px solid transparent;border-radius:50%;background:none;color:var(--muted);cursor:pointer}
.icon-btn:hover{color:var(--accent);border-color:var(--line)}
.icon-btn .icon{width:18px;height:18px}
.icon-sun{display:none}
[data-theme="dark"] .icon-sun{display:block}
[data-theme="dark"] .icon-moon{display:none}

/* hero */
.hero{padding:76px 0 60px}
.epigraph{font-family:var(--serif);font-size:1.2rem;color:var(--muted);letter-spacing:.06em;margin-bottom:22px}
.hero h1{font-family:var(--serif);font-weight:600;font-size:clamp(2.6rem,7vw,4rem);
  line-height:1.35;letter-spacing:-.01em}
.hero h1 .accent{color:var(--accent)}
.lede{color:var(--muted);font-size:1.05rem;margin-top:18px;max-width:34em}
.stats{margin-top:26px;font-size:.8rem;color:var(--muted);letter-spacing:.06em}

/* sections */
.section{padding:8px 0 56px}
.section-head{display:flex;align-items:baseline;justify-content:space-between;gap:16px;
  border-top:2px solid var(--ink);padding:16px 0 6px;margin-bottom:6px}
.section-title{font-family:var(--serif);font-size:1.45rem;font-weight:600}
.section-head a{font-size:.85rem;color:var(--muted);white-space:nowrap}
.section-head a:hover{color:var(--accent)}

/* featured */
.featured{display:grid;grid-template-columns:300px minmax(0,1fr);gap:36px;align-items:start;
  padding:30px 0;border-top:1px solid var(--line)}
.featured-img{overflow:hidden;border-radius:4px;background:var(--surface);aspect-ratio:3/2}
.featured-img img{width:100%;height:100%;object-fit:cover;transition:transform .5s ease}
.featured-img:hover img{transform:scale(1.03)}
.featured-text .kicker{margin-bottom:14px;display:block}
.featured-text h2{font-family:var(--serif);font-size:1.9rem;line-height:1.5;font-weight:600;margin-bottom:12px}
.featured-text h2 a:hover{color:var(--accent)}
.featured-text>p{color:var(--muted);font-size:1rem;max-width:36em}
.featured-meta{margin-top:16px;font-size:.78rem;color:var(--muted);letter-spacing:.04em}

/* numbered index */
.idx-row{display:grid;grid-template-columns:64px minmax(0,1fr);gap:6px 20px;align-items:baseline;
  padding:22px 4px;border-top:1px solid var(--line)}
.idx li:last-child .idx-row{border-bottom:1px solid var(--line)}
.idx-num{font-family:var(--mono);font-size:1rem;color:var(--muted);font-variant-numeric:tabular-nums}
.idx-title{font-family:var(--serif);font-size:1.4rem;font-weight:600;line-height:1.55}
.idx-row:hover .idx-title{color:var(--accent)}
.idx-meta{display:block;font-size:.78rem;color:var(--muted);margin-top:8px;letter-spacing:.03em}
.idx-meta .cat{color:var(--accent);font-weight:600}

/* notes */
.note-teasers li{display:grid;grid-template-columns:110px minmax(0,1fr);gap:18px;
  padding:18px 4px;border-top:1px solid var(--line);align-items:baseline}
.note-teasers li:last-child{border-bottom:1px solid var(--line)}
.note-teasers time{font-size:.8rem;color:var(--muted)}
.note-teasers p{font-size:1rem;line-height:1.9}
.note{display:grid;grid-template-columns:120px minmax(0,1fr);gap:20px;
  padding:26px 4px;border-top:1px solid var(--line);align-items:baseline}
.note:last-of-type{border-bottom:1px solid var(--line)}
.note time{font-size:.82rem;color:var(--muted)}
.note p{font-family:var(--serif);font-size:1.12rem;line-height:1.95}
.note .note-tag{font-family:var(--mono);font-size:.75rem;color:var(--muted);margin-top:10px;letter-spacing:.1em}

/* page head */
.page-head{padding:64px 0 40px}
.page-head h1{font-family:var(--serif);font-size:clamp(2.2rem,5.5vw,3rem);font-weight:600;
  line-height:1.4;margin:18px 0 12px}

/* archive */
.year-head{display:flex;align-items:baseline;gap:18px;margin:10px 0 4px}
.year-head h2{font-family:var(--serif);font-size:2.2rem;font-weight:600}
.year-head span{font-size:.8rem;color:var(--muted)}

/* about */
.about-hero{display:grid;grid-template-columns:minmax(0,1fr) 150px;gap:48px;align-items:start;
  padding:20px 0 8px}
.about-hero h2{font-family:var(--serif);font-size:clamp(1.9rem,4.5vw,2.6rem);font-weight:600;
  line-height:1.5;margin-bottom:20px}
.about-hero p{color:var(--muted);margin-bottom:18px;max-width:36em}
.monogram{width:150px;height:150px;border:1px solid var(--line);border-radius:50%;
  display:flex;align-items:center;justify-content:center;
  font-family:var(--serif);font-size:3.4rem;color:var(--accent)}
.contact-block{border-top:2px solid var(--ink);margin-top:44px;padding-top:26px}
.contact-block .kicker{display:block;margin-bottom:14px}
.contact-block>a{font-family:var(--serif);font-size:1.5rem;color:var(--accent);overflow-wrap:anywhere}
.contact-block p{color:var(--muted);margin-top:10px;font-size:1rem}

/* article */
.article{padding-bottom:80px}
.back{display:inline-block;font-size:.82rem;color:var(--muted);margin:34px 0 0;letter-spacing:.04em}
.back:hover{color:var(--accent)}
.article-head{max-width:700px;margin:36px 0 0}
.article-head .kicker{display:block;margin-bottom:16px}
.article-head .kicker .cat{color:var(--accent);font-weight:600}
.article-head h1{font-family:var(--serif);font-size:clamp(2rem,5vw,2.9rem);font-weight:600;
  line-height:1.45;letter-spacing:.01em}
.deck{color:var(--muted);font-size:1.08rem;margin-top:16px;max-width:38em}
.byline{display:flex;align-items:center;gap:12px;margin-top:26px;font-size:.85rem;color:var(--muted)}
.avatar{display:inline-flex;align-items:center;justify-content:center;width:30px;height:30px;
  border-radius:50%;background:var(--surface);color:var(--accent);font-weight:700;font-size:.8rem}
.byline time{font-family:var(--mono);font-size:.8rem}
.byline .sep{color:var(--line)}

.article-grid{display:grid;grid-template-columns:190px minmax(0,700px);gap:60px;
  justify-content:center;margin-top:44px}
.toc{position:sticky;top:28px;align-self:start}
.toc .kicker{display:block;margin-bottom:14px}
.toc a{display:block;font-size:.88rem;color:var(--muted);line-height:1.7;
  border-left:2px solid transparent;padding:7px 0 7px 14px;margin-left:-16px}
.toc a:hover{color:var(--accent)}
.toc a[aria-current="location"]{color:var(--accent);border-left-color:var(--accent)}

.prose{min-width:0;font-size:1.125rem}
.prose section{margin-bottom:8px}
.prose h2{font-family:var(--serif);font-size:1.6rem;font-weight:600;margin:2.2em 0 .9em;line-height:1.5}
.prose p{margin-bottom:1.4em}
.prose p:last-child{margin-bottom:0}
.dropcap::first-letter{font-family:var(--serif);font-size:3.2em;float:left;line-height:1;
  margin:.08em .14em 0 0;color:var(--ink);font-weight:600}
.prose figure{margin:2.6em 0}
.prose figure img{width:100%;border-radius:4px}
.prose figcaption{font-family:var(--mono);font-size:.76rem;color:var(--muted);text-align:center;
  padding-top:12px;letter-spacing:.03em}
.prose a{color:var(--accent);text-decoration:underline;text-underline-offset:4px}

.article-end{text-align:center;margin:64px 0 0}
.article-end .end-mark{font-family:var(--serif);color:var(--muted);letter-spacing:.35em;font-size:.9rem}
.article-end a{display:inline-block;margin-top:22px;font-size:.9rem;color:var(--accent)}

.pager{display:grid;grid-template-columns:1fr 1fr;gap:24px;border-top:2px solid var(--ink);
  margin-top:56px;padding-top:24px}
.pager a{display:block}
.pager .kicker{display:block;margin-bottom:10px}
.pager .next{text-align:right}
.pager strong{font-family:var(--serif);font-weight:600;font-size:1.1rem;line-height:1.6;display:block}
.pager a:hover strong{color:var(--accent)}

/* progress bar (created by JS) */
.progress{position:fixed;top:0;left:0;height:3px;width:0;background:var(--accent);z-index:55}

/* sample disclosure */
.sample-banner{background:var(--surface);border-left:3px solid var(--accent);
  padding:12px 18px;font-size:.88rem;color:var(--muted);margin-bottom:34px}
.sample-disclosure{color:var(--muted);font-size:.82rem;margin:40px 0 64px;font-family:var(--mono);
  letter-spacing:.02em}

/* footer */
.site-footer{border-top:1px solid var(--line);margin-top:20px}
.footer-inner{display:flex;align-items:center;gap:26px;flex-wrap:wrap;
  padding:28px 0 36px;color:var(--muted);font-size:.88rem}
.footer-brand{font-family:var(--serif);font-weight:700;font-size:1.1rem;color:var(--ink);margin-right:auto}
.footer-brand small{font-family:var(--sans);font-weight:400;font-size:.8rem;margin-left:12px;color:var(--muted)}
.footer-inner a:hover{color:var(--accent)}

/* 404 */
.not-found{padding:110px 0 140px;max-width:700px}
.not-found h1{font-family:var(--serif);font-size:clamp(2.2rem,6vw,3.2rem);font-weight:600;
  margin:20px 0 14px;line-height:1.4}
.not-found p{color:var(--muted);margin-bottom:34px}
.button{display:inline-block;background:var(--accent);color:#fff;padding:13px 30px;
  font-size:.95rem;border-radius:4px}
.button:hover{color:#fff;opacity:.88}
[data-theme="dark"] .button{color:#141412}

/* responsive */
@media(max-width:1000px){
  .article-grid{grid-template-columns:minmax(0,700px);justify-content:start;gap:0}
  .toc{position:static;display:flex;flex-wrap:wrap;gap:4px 18px;align-items:baseline;
    border-top:1px solid var(--line);border-bottom:1px solid var(--line);
    padding:16px 0;margin-bottom:36px}
  .toc .kicker{flex-basis:100%;margin-bottom:6px}
  .toc a{border-left:none;padding:4px 0;margin:0}
  .toc a[aria-current="location"]{border-left:none}
  .featured{grid-template-columns:260px minmax(0,1fr);gap:28px}
}
@media(max-width:720px){
  body{font-size:1.0625rem}
  .masthead-inner{height:68px}
  .wordmark{font-size:1.25rem}
  .site-nav{gap:16px;font-size:.88rem}
  .nav-icons{margin-left:2px;padding-left:10px}
  .hero{padding:52px 0 44px}
  .featured{grid-template-columns:1fr;gap:20px}
  .featured-img{max-width:420px}
  .featured-text h2{font-size:1.6rem}
  .idx-row{grid-template-columns:44px minmax(0,1fr);gap:4px 14px;padding:18px 2px}
  .idx-title{font-size:1.2rem}
  .note-teasers li,.note{grid-template-columns:1fr;gap:8px}
  .about-hero{grid-template-columns:1fr;gap:28px}
  .monogram{width:110px;height:110px;font-size:2.6rem}
  .pager{grid-template-columns:1fr}
  .pager .next{text-align:left}
  .article-head h1{line-height:1.5}
}