:root{--brand:#e80b2d;--brand-dark:#c10824;--ink:#0f172a;--muted:#64748b;--line:#e2e8f0;--soft:#f8fafc;--card:#fff;--radius:16px;font-family:Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;color:var(--ink);background:#fff}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;line-height:1.7;background:#fff}a{color:var(--brand);text-underline-offset:3px}a:hover{color:var(--brand-dark)}img{max-width:100%;height:auto}
.wrap{max-width:1120px;margin:0 auto;padding:0 20px}.narrow{max-width:760px;margin:0 auto;padding:0 20px}
header.site{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.92);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
header.site .wrap{display:flex;align-items:center;justify-content:space-between;gap:16px;min-height:64px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;font-size:1.2rem;color:var(--ink);text-decoration:none}.brand img{width:32px;height:32px}
.links{display:flex;align-items:center;gap:22px}.links a{color:#334155;text-decoration:none;font-size:.93rem;font-weight:500}.links a:hover{color:var(--brand)}
.btn{display:inline-flex;align-items:center;gap:8px;background:var(--brand);color:#fff!important;padding:10px 20px;border-radius:12px;font-weight:700;text-decoration:none!important;border:0;cursor:pointer;font-size:.95rem;box-shadow:0 6px 18px rgba(232,11,45,.22)}.btn:hover{background:var(--brand-dark)}
.btn.ghost{background:#fff;color:var(--ink)!important;border:1px solid var(--line);box-shadow:none}.btn.ghost:hover{background:var(--soft)}
.hero{background:linear-gradient(180deg,#fff5f6 0,#fff 100%);padding:56px 0 36px;border-bottom:1px solid var(--line)}
.eyebrow{display:inline-block;text-transform:uppercase;letter-spacing:.14em;color:var(--brand);font-weight:800;font-size:.76rem}
h1{font-size:clamp(2rem,4.6vw,3.2rem);line-height:1.12;letter-spacing:-.035em;margin:10px 0 14px;font-weight:850}
h2{font-size:1.6rem;line-height:1.25;letter-spacing:-.02em;margin:0 0 12px;font-weight:800}h3{font-size:1.15rem;margin:0 0 8px;font-weight:700}
.lead{font-size:1.15rem;color:#475569;max-width:720px}
.crumbs{font-size:.85rem;color:var(--muted);margin-bottom:10px}.crumbs a{color:#475569;text-decoration:none}.crumbs a:hover{color:var(--brand)}
.grid{display:grid;gap:22px;grid-template-columns:repeat(auto-fill,minmax(300px,1fr))}
.card{display:flex;flex-direction:column;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;text-decoration:none;color:inherit;transition:transform .15s,box-shadow .15s}
.card:hover{transform:translateY(-3px);box-shadow:0 14px 34px rgba(15,23,42,.1);color:inherit}
.card .cover{aspect-ratio:16/9;background:linear-gradient(135deg,#ffe4e8,#fff);object-fit:cover;width:100%}.card .cover.ph{display:grid;place-items:center;font-size:2.4rem}
.card .body{padding:18px 20px 20px;display:flex;flex-direction:column;gap:8px;flex:1}.card h3{margin:0;font-size:1.1rem;line-height:1.35;color:var(--ink)}.card p{margin:0;color:#475569;font-size:.93rem}
.meta{display:flex;flex-wrap:wrap;gap:6px 12px;font-size:.8rem;color:var(--muted)}.tag{display:inline-block;background:#fff1f3;color:var(--brand);border-radius:999px;padding:2px 10px;font-size:.75rem;font-weight:600;text-decoration:none}
.pills{display:flex;flex-wrap:wrap;gap:8px;margin:18px 0 0}.pill{border:1px solid var(--line);background:#fff;border-radius:999px;padding:6px 14px;font-size:.88rem;color:#334155;text-decoration:none;font-weight:500}.pill:hover,.pill.on{background:var(--brand);border-color:var(--brand);color:#fff}
main.page{padding:36px 0 70px}.section{margin:46px 0}
.post-head{padding:44px 0 8px}.post-cover{border-radius:20px;margin:24px 0 8px;width:100%;aspect-ratio:16/9;object-fit:cover}
.post-layout{display:grid;grid-template-columns:minmax(0,1fr) 260px;gap:48px;align-items:start}
.toc{position:sticky;top:84px;border:1px solid var(--line);border-radius:var(--radius);padding:18px 20px;background:var(--soft);font-size:.9rem}.toc strong{display:block;margin-bottom:8px;font-size:.78rem;text-transform:uppercase;letter-spacing:.1em;color:var(--muted)}.toc ul{list-style:none;padding:0;margin:0}.toc li{margin:7px 0;line-height:1.4}.toc li.l3{padding-left:14px}.toc a{color:#334155;text-decoration:none}.toc a:hover{color:var(--brand)}
.prose{font-size:1.07rem;line-height:1.85}.prose>*+*{margin-top:1.05rem}.prose h2{margin-top:2.4rem;scroll-margin-top:84px}.prose h3{margin-top:1.8rem;scroll-margin-top:84px}
.prose ul{list-style:disc;padding-left:1.4rem}.prose ol{list-style:decimal;padding-left:1.4rem}.prose li+li{margin-top:.4rem}
.prose blockquote{border-left:4px solid var(--brand);background:#fff5f6;margin-left:0;padding:.9rem 1.2rem;border-radius:0 12px 12px 0;font-style:italic}
.prose pre{background:#0f172a;color:#e2e8f0;padding:1rem;border-radius:12px;overflow-x:auto;font-size:.9rem}.prose hr{border:0;border-top:1px solid var(--line);margin:2.2rem 0}
.prose img{display:block;margin:1.6rem auto;border-radius:14px}.prose img[data-size=sm]{width:33%}.prose img[data-size=md]{width:55%}.prose img[data-size=lg]{width:80%}
.prose table{width:100%;border-collapse:collapse;display:block;overflow-x:auto;font-size:.95rem}.prose th,.prose td{border:1px solid var(--line);padding:.6rem .8rem;text-align:left;vertical-align:top}.prose th{background:var(--soft);font-weight:700}
.prose iframe{width:100%;aspect-ratio:16/9;height:auto;border:0;border-radius:14px}.prose [style*="text-align: center"]{text-align:center}
.box{border:1px solid var(--line);border-radius:var(--radius);padding:22px 24px;background:#fff}.box.tip{background:#fff8eb;border-color:#f6dfae}.box.good{background:#f0fdf4;border-color:#bbf7d0}
.cta{margin:48px 0 0;border-radius:22px;padding:34px;background:linear-gradient(135deg,#e80b2d,#ff5a72);color:#fff;display:flex;flex-wrap:wrap;gap:20px;align-items:center;justify-content:space-between}.cta h2{color:#fff;margin:0 0 6px}.cta p{margin:0;opacity:.92}.cta .btn{background:#fff;color:var(--brand)!important;box-shadow:none}
.vocab{display:grid;gap:10px;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));list-style:none;padding:0}.vocab li{border:1px solid var(--line);border-radius:12px;padding:10px 14px;margin:0!important}.vocab b{color:var(--brand)}
.qa{border:1px solid var(--line);border-radius:14px;padding:16px 20px;margin:12px 0;background:#fff}.qa h3{margin:0 0 6px}.qa p{margin:0;color:#334155}
details.faq{border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin:10px 0;background:#fff}details.faq summary{cursor:pointer;font-weight:700}
.pager{display:flex;justify-content:center;gap:10px;margin-top:34px}
footer.site{border-top:1px solid var(--line);background:var(--soft);padding:40px 0 30px;color:#475569;font-size:.9rem}footer.site .cols{display:grid;gap:28px;grid-template-columns:repeat(auto-fit,minmax(180px,1fr))}footer.site h4{margin:0 0 10px;color:var(--ink);font-size:.9rem}footer.site a{display:block;color:#475569;text-decoration:none;margin:6px 0}footer.site a:hover{color:var(--brand)}footer.site .copy{margin-top:26px;padding-top:18px;border-top:1px solid var(--line);color:var(--muted)}
.calc{display:grid;gap:14px;grid-template-columns:repeat(auto-fit,minmax(150px,1fr))}.calc label{font-size:.85rem;font-weight:600;color:#334155;display:block}.calc select{width:100%;padding:10px;border-radius:10px;border:1px solid var(--line);font-size:1rem;margin-top:4px;background:#fff}
.result{font-size:3rem;font-weight:850;color:var(--brand);line-height:1}
@media(max-width:860px){.post-layout{grid-template-columns:1fr}.toc{position:static}.links a:not(.btn){display:none}.cta{padding:26px}.prose img[data-size=sm],.prose img[data-size=md]{width:70%}}
figure.chart{margin:22px 0;padding:18px;border:1px solid var(--line);border-radius:var(--radius);background:#fff}figure.chart figcaption{font-weight:700;margin-bottom:10px;color:var(--ink)}figure.chart svg{width:100%;height:auto;display:block}
.table-scroll{overflow-x:auto}table.data{width:100%;border-collapse:collapse;font-size:.95rem}table.data th,table.data td{border:1px solid var(--line);padding:.55rem .8rem;text-align:left}table.data thead th{background:var(--soft)}
.hubs{display:grid;gap:18px;grid-template-columns:repeat(auto-fill,minmax(260px,1fr))}.hub{display:flex;flex-direction:column;gap:6px;border:1px solid var(--line);border-radius:var(--radius);padding:20px;background:#fff;text-decoration:none;color:inherit;transition:transform .15s,box-shadow .15s}.hub:hover{transform:translateY(-3px);box-shadow:0 14px 34px rgba(15,23,42,.1);color:inherit}.hub .ico{width:46px;height:46px;border-radius:14px;background:#fff1f3;display:grid;place-items:center;font-size:1.5rem}.hub h3{margin:6px 0 0;font-size:1.1rem}.hub p{margin:0;color:#475569;font-size:.92rem}.hub .count{margin-top:auto;font-size:.8rem;font-weight:700;color:var(--brand)}
.section-head{display:flex;justify-content:space-between;align-items:baseline;gap:12px;margin-bottom:16px}.section-head h2{margin:0}.section-head a{font-size:.9rem;font-weight:600}
.feature{display:grid;grid-template-columns:1.3fr 1fr;gap:0;border:1px solid var(--line);border-radius:22px;overflow:hidden;text-decoration:none;color:inherit;background:#fff}.feature:hover{color:inherit;box-shadow:0 14px 34px rgba(15,23,42,.1)}.feature img{width:100%;height:100%;object-fit:cover;min-height:240px}.feature .body{padding:30px;display:flex;flex-direction:column;gap:10px;justify-content:center}.feature h3{font-size:1.5rem;line-height:1.25;margin:0}
@media(max-width:860px){.feature{grid-template-columns:1fr}}

/* Phone bottom bar for server-rendered pages (shown by a script when the visitor is signed in) */
.bnav{display:none}
@media(max-width:860px){.bnav.show{display:block;position:fixed;left:0;right:0;bottom:0;z-index:50;padding:0 12px calc(12px + env(safe-area-inset-bottom))}
.bnav-in{display:flex;align-items:flex-end;justify-content:space-around;height:64px;padding:0 8px;border-radius:18px;background:rgba(255,255,255,.96);backdrop-filter:blur(14px);border:1px solid var(--line);box-shadow:0 10px 30px rgba(15,23,42,.14)}
.bnav a{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:2px;height:100%;color:var(--muted);text-decoration:none;font-size:10px;font-weight:600}
.bnav a.on{color:var(--brand)}
.bnav a[data-learn]{position:relative;margin-top:-24px;color:#fff;height:auto}
.bnav a[data-learn] svg{box-sizing:content-box;padding:15px;border-radius:18px;background:linear-gradient(135deg,var(--brand),#ff5a72);box-shadow:0 8px 20px rgba(232,11,45,.35),0 0 0 4px #fff}
.bnav a[data-learn] span{color:var(--brand);margin-top:2px}
body.has-bnav{padding-bottom:96px}}
.links a.sec{color:#64748b;font-size:.82rem;border-left:1px solid var(--line);padding-left:14px}
@media(max-width:1180px){.links{gap:14px}.links a.sec{display:none}}