:root{--bg:#fff;--soft:#f8fafc;--ink:#0f172a;--mut:#475569;--line:#e2e8f0;--ac:#4f46e5;--ac2:#0ea5e9;--ok:#16a34a;--r:14px;--sh:0 1px 2px rgba(15,23,42,.06),0 8px 24px -12px rgba(15,23,42,.18);--w:1160px}
*{box-sizing:border-box}html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{margin:0;font:17px/1.7 system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;color:var(--ink);background:var(--bg)}
img,svg{max-width:100%;height:auto}a{color:var(--ac);text-underline-offset:3px}a:hover{color:#3730a3}
.wrap{max-width:var(--w);margin:0 auto;padding:0 20px}.narrow{max-width:800px;margin:0 auto;padding:0 20px}
.skip{position:absolute;left:-999px}.skip:focus{left:12px;top:12px;background:#fff;padding:8px 12px;z-index:99}
.site-header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.88);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.hdr{display:flex;align-items:center;justify-content:space-between;height:64px;gap:16px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);font-weight:700;font-size:19px;letter-spacing:-.01em}.brand b{color:var(--ac)}
.nav{display:flex;gap:4px;flex-wrap:wrap}.nav a{color:var(--ink);text-decoration:none;font-size:15px;font-weight:600;padding:8px 12px;border-radius:999px}.nav a:hover{background:var(--soft);color:var(--ac)}
h1,h2,h3{line-height:1.2;letter-spacing:-.02em}
.kicker{display:inline-block;margin:0 0 12px;font-size:13px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--c,var(--ac))}
/* home hero */
.hero-home{background:radial-gradient(1200px 400px at 85% -10%,#e0e7ff 0,transparent 60%),radial-gradient(900px 400px at 0 0,#e0f2fe 0,transparent 55%),var(--soft);border-bottom:1px solid var(--line)}
.hh{padding:72px 20px 56px}.hh h1{font-size:clamp(34px,5.2vw,58px);margin:0 0 18px;max-width:900px}
.lead{font-size:clamp(18px,2.2vw,21px);color:var(--mut);max-width:760px;margin:0 0 28px}
.hh-cta{display:flex;gap:12px;flex-wrap:wrap;margin-bottom:36px}
.btn{display:inline-block;background:var(--ac);color:#fff;text-decoration:none;font-weight:700;padding:13px 22px;border-radius:999px;box-shadow:0 8px 20px -8px rgba(79,70,229,.6)}.btn:hover{background:#3730a3;color:#fff}
.btn.ghost{background:#fff;color:var(--ink);box-shadow:none;border:1px solid var(--line)}.btn.ghost:hover{border-color:var(--ac);color:var(--ac)}
.stats{list-style:none;display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:14px;padding:0;margin:0}
.stats li{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:16px 18px}.stats b{display:block;font-size:30px;letter-spacing:-.02em;color:var(--ac)}.stats span{font-size:14px;color:var(--mut);line-height:1.4;display:block}
.sec{font-size:28px;margin:48px 0 20px}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:16px}
.ecard{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:18px;box-shadow:var(--sh);border-top:4px solid var(--c);display:flex;flex-direction:column;gap:16px;transition:transform .15s}.ecard:hover{transform:translateY(-2px)}
.ec-top{display:flex;gap:12px;align-items:center}.ec-top h3{margin:0;font-size:18px}.ec-top p{margin:0;font-size:14px;color:var(--mut)}
.ec-dot{width:44px;height:44px;border-radius:12px;background:var(--c);color:#fff;font-weight:800;font-size:20px;display:grid;place-items:center;flex:none}
.ec-links{display:flex;gap:8px;flex-wrap:wrap}.btn-s{font-size:14px;font-weight:700;text-decoration:none;background:var(--c);color:#fff;padding:8px 14px;border-radius:999px}.btn-s.alt{background:var(--soft);color:var(--ink);border:1px solid var(--line)}.btn-s:hover{filter:brightness(.92);color:#fff}.btn-s.alt:hover{color:var(--ink)}
/* article */
.crumbs{font-size:14px;color:var(--mut);padding-top:18px;padding-bottom:6px}.crumbs a{color:var(--mut);text-decoration:none}.crumbs a:hover{color:var(--ac)}.crumbs i{opacity:.5;font-style:normal;margin:0 4px}
.art-head{padding-top:10px;padding-bottom:6px}.art-head h1{max-width:900px}.art-head h1,.page-head h1{font-size:clamp(30px,4.4vw,46px);margin:0 0 14px}
.page-head{padding-top:14px;padding-bottom:6px;max-width:800px;margin:0 auto}
.byline{color:var(--mut);font-size:15px;margin:0 0 22px}.byline span{opacity:.5;margin:0 4px}.byline a{color:var(--ink);font-weight:600;text-decoration:none}
.hero{margin:0 0 8px}.hero img{width:100%;border-radius:18px;box-shadow:var(--sh);display:block}
.art-grid{display:grid;grid-template-columns:260px minmax(0,1fr);gap:48px;align-items:start;padding-top:24px;padding-bottom:64px}
.toc{position:sticky;top:84px;font-size:15px;border:1px solid var(--line);border-radius:var(--r);padding:14px 16px;background:var(--soft)}
.toc summary{font-weight:700;cursor:pointer}.toc ol{margin:10px 0 0;padding-left:18px}.toc li{margin:6px 0}.toc a{color:var(--mut);text-decoration:none}.toc a:hover{color:var(--ac)}
.prose{max-width:760px;min-width:0}.prose h2{font-size:30px;margin:2.2em 0 .6em;scroll-margin-top:84px}.prose h3{font-size:21px;margin:1.6em 0 .4em;scroll-margin-top:84px}
.prose p,.prose li{overflow-wrap:anywhere}.prose ul,.prose ol{padding-left:1.3em}.prose li{margin:.35em 0}
.prose strong{font-weight:700}.prose u{text-decoration-color:var(--ac2);text-decoration-thickness:3px;text-underline-offset:4px}
.prose code{background:#eef2ff;padding:.12em .4em;border-radius:6px;font-size:.9em}
.prose pre{background:#0f172a;color:#e2e8f0;padding:16px 18px;border-radius:12px;overflow:auto;font-size:14.5px;line-height:1.55}.prose pre code{background:none;padding:0;color:inherit}
.prose blockquote{margin:1.4em 0;padding:4px 18px;border-left:4px solid var(--ac);background:var(--soft);border-radius:0 12px 12px 0;color:#1e293b}
.takeaways{background:linear-gradient(180deg,#eef2ff,#f8fafc);border:1px solid #c7d2fe;border-radius:var(--r);padding:18px 22px;margin:1.6em 0}.takeaways .tk-title{margin:0 0 6px;font-weight:800;color:var(--ac);text-transform:uppercase;font-size:13px;letter-spacing:.08em}.takeaways ul{margin:6px 0 0}
.table-wrap{overflow-x:auto;margin:1.4em 0;border:1px solid var(--line);border-radius:12px}.prose table{border-collapse:collapse;width:100%;font-size:15.5px;min-width:520px}
.prose th{background:var(--soft);text-align:left;font-weight:700}.prose th,.prose td{padding:11px 14px;border-bottom:1px solid var(--line);vertical-align:top}.prose tr:last-child td{border-bottom:0}
figure{margin:1.8em 0}figure img{border:1px solid var(--line);border-radius:14px;background:var(--soft);display:block;width:100%}figcaption{font-size:14px;color:var(--mut);margin-top:8px;text-align:center}
.next-read{margin-top:3em;border-top:1px solid var(--line);padding-top:8px}.cta{display:block;text-decoration:none;color:#fff;background:linear-gradient(135deg,var(--ac),#3730a3);padding:20px 24px;border-radius:var(--r);margin:16px 0}.cta span{display:block;font-size:13px;letter-spacing:.08em;text-transform:uppercase;opacity:.85}.cta b{font-size:20px;line-height:1.3}
.rels{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:12px}.rel{display:block;text-decoration:none;color:var(--ink);border:1px solid var(--line);border-radius:12px;padding:14px 16px;background:#fff}.rel:hover{border-color:var(--ac)}.rel span{display:block;font-size:13px;color:var(--ac);font-weight:700}.rel b{font-size:15.5px;line-height:1.35}
.author-box{display:flex;gap:16px;align-items:flex-start;background:var(--soft);border:1px solid var(--line);border-radius:var(--r);padding:18px;margin-top:32px}.author-box p{margin:0 0 4px;font-size:15.5px}.author-box .an{font-weight:700}
.av{width:52px;height:52px;border-radius:50%;background:var(--ac);color:#fff;display:grid;place-items:center;font-weight:800;flex:none}.av.big{width:84px;height:84px;font-size:28px;margin-bottom:12px}
.pn{display:flex;justify-content:space-between;gap:12px;margin-top:28px;font-weight:600;font-size:15px}.pn a{text-decoration:none}
.home-prose{max-width:800px}
.site-footer{background:#0f172a;color:#cbd5e1;padding:48px 0 28px;margin-top:40px}.site-footer a{color:#e2e8f0;text-decoration:none}.site-footer a:hover{color:#fff;text-decoration:underline}.site-footer .brand{color:#fff}.site-footer .brand b{color:#818cf8}
.foot-grid{display:grid;grid-template-columns:1.3fr 1fr 1fr 1fr;gap:28px}.site-footer h3{color:#fff;font-size:15px;margin:0 0 12px}.site-footer ul{list-style:none;padding:0;margin:0;font-size:14.5px;line-height:2}.site-footer .muted{font-size:14.5px;color:#94a3b8}.copy{border-top:1px solid #1e293b;margin-top:28px;padding-top:18px;font-size:13.5px;color:#94a3b8}
@media(max-width:980px){.art-grid{grid-template-columns:1fr;gap:20px}.toc{position:static}.foot-grid{grid-template-columns:1fr 1fr}}
@media(max-width:620px){body{font-size:16.5px}.nav a{padding:6px 8px;font-size:14px}.hdr{height:auto;padding:10px 20px;flex-direction:column;align-items:flex-start}.foot-grid{grid-template-columns:1fr}.prose h2{font-size:25px}.hh{padding-top:44px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.ecard{transition:none}}