:root{
  --bg:#ffffff; --surface:#f5f7fa; --text:#1c2430; --muted:#5a6676; --line:#e2e7ee;
  --brand:#1f5f8b; --brand-ink:#ffffff; --link:#1d5c86; --note:#fff8e6; --note-line:#f0d58a;
  --radius:12px; --max:1120px; --prose:720px;
  color-scheme:light;
}
@media (prefers-color-scheme:dark){
  :root{--bg:#10151c; --surface:#18202a; --text:#e6ebf1; --muted:#a3afbd; --line:#283341;
    --brand:#4d93c4; --brand-ink:#0b1016; --link:#8cc3ea; --note:#2a2414; --note-line:#6b5a25; color-scheme:dark}
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--text);
  font:17px/1.65 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif}
a{color:var(--link)}
a:hover{text-decoration-thickness:2px}
img{max-width:100%;height:auto}
.wrap{max-width:var(--max);margin:0 auto;padding:0 16px}
.skip{position:absolute;left:-999px;top:0;background:var(--brand);color:var(--brand-ink);padding:8px 12px;z-index:9}
.skip:focus{left:8px}

.site-header{border-bottom:1px solid var(--line);background:var(--bg);position:sticky;top:0;z-index:5}
.site-header .wrap{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;padding:10px 16px}
.brand{display:flex;align-items:center;gap:10px;font-weight:700;font-size:1.15rem;color:var(--text);text-decoration:none}
.logo{display:inline-grid;place-items:center;width:34px;height:34px;border-radius:9px;background:var(--brand);
  color:var(--brand-ink);font-family:Georgia,serif;font-size:1.2rem}
.site-header nav ul{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:4px 18px}
.site-header nav a{color:var(--muted);text-decoration:none;font-size:.95rem;padding:6px 0;display:inline-block}
.site-header nav a:hover{color:var(--text)}

.hero{padding:44px 0 18px;max-width:800px}
.hero h1{font-size:clamp(1.9rem,4vw,2.6rem);line-height:1.15;margin:0 0 12px}
.hero p{margin:0 0 10px;font-size:1.15rem;color:var(--muted)}
.hero .hero-sub{font-size:.98rem}

section{margin:28px 0}
.cat-head{display:flex;align-items:baseline;justify-content:space-between;gap:12px;border-bottom:1px solid var(--line);
  padding-bottom:6px;margin-bottom:14px}
.cat-head h2{margin:0;font-size:1.35rem}
.cat-head h2 a{color:var(--text);text-decoration:none}
.cat-intro{color:var(--muted);margin:-4px 0 14px;font-size:.98rem}
.more{font-size:.95rem;text-decoration:none;white-space:nowrap}

.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(290px,1fr));gap:16px}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:18px 18px 14px;
  display:flex;flex-direction:column}
.card h3{margin:2px 0 8px;font-size:1.12rem;line-height:1.35}
.card h3 a{color:var(--text);text-decoration:none}
.card h3 a:hover{color:var(--link);text-decoration:underline}
.card .excerpt{margin:0 0 10px;color:var(--muted);font-size:.95rem;flex:1}
.kicker{margin:0;font-size:.78rem;font-weight:700;letter-spacing:.06em;text-transform:uppercase}
.kicker a{text-decoration:none}
.meta{margin:0;color:var(--muted);font-size:.86rem}

.list-head{padding:34px 0 6px;max-width:800px}
.list-head h1{margin:0 0 8px;font-size:clamp(1.7rem,3.5vw,2.2rem)}
.list-head p{margin:0;color:var(--muted)}

.article-wrap{max-width:calc(var(--prose) + 32px)}
.crumbs{font-size:.88rem;color:var(--muted);padding:20px 0 0}
.crumbs a{color:var(--muted)}
.post-head{padding:14px 0 6px}
.post-head h1{font-size:clamp(1.75rem,4vw,2.35rem);line-height:1.2;margin:6px 0 12px}
.lede{font-size:1.15rem;color:var(--muted);margin:0 0 12px}
.toc{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:14px 18px;margin:18px 0}
.toc p{margin:0 0 6px;font-weight:700;font-size:.95rem}
.toc ol{margin:0;padding-left:20px;font-size:.95rem}
.toc li{margin:3px 0}

.prose h2{font-size:1.45rem;line-height:1.3;margin:34px 0 10px;scroll-margin-top:80px}
.prose h3{font-size:1.15rem;margin:24px 0 6px}
.prose p,.prose ul,.prose ol{margin:0 0 14px}
.prose li{margin:4px 0}
.prose table{width:100%;border-collapse:collapse;margin:8px 0 18px;font-size:.95rem;display:block;overflow-x:auto}
.prose th,.prose td{border:1px solid var(--line);padding:8px 10px;text-align:left;vertical-align:top}
.prose th{background:var(--surface)}
.prose .takeaways{background:var(--surface);border-left:4px solid var(--brand);border-radius:8px;padding:12px 18px;margin:18px 0}
.prose .takeaways h2{margin-top:6px;font-size:1.15rem}
.prose .example{border:1px dashed var(--line);border-radius:8px;padding:12px 16px;margin:16px 0;background:var(--surface)}
.prose .faq h3{margin-top:18px}
.prose .sources{font-size:.92rem;color:var(--muted)}
.prose .sources li{word-break:break-word}
.note{background:var(--note);border:1px solid var(--note-line);border-radius:var(--radius);padding:14px 18px;
  margin:30px 0 10px;font-size:.92rem}
.related h2{font-size:1.3rem}

.site-footer{border-top:1px solid var(--line);margin-top:48px;padding:24px 0 34px;background:var(--surface);font-size:.92rem;color:var(--muted)}
.foot-note{max-width:760px;margin:0 0 12px}
.foot-links{list-style:none;padding:0;margin:0 0 10px;display:flex;flex-wrap:wrap;gap:6px 18px}
.copy{margin:0}

@media (max-width:640px){
  body{font-size:16.5px}
  .site-header{position:static}
  .site-header nav ul{gap:2px 14px}
  .hero{padding-top:28px}
}