:root{color-scheme:dark;--bg:#09090b;--panel:#121216;--line:rgba(255,255,255,.12);--text:#f7f7f8;--muted:#aaaab4;--accent:#34d399}*{box-sizing:border-box}body.seo-body{margin:0;background:radial-gradient(80rem 34rem at 50% -10%,#17342d 0%,var(--bg) 57%);color:var(--text);font:16px/1.65 Inter,ui-sans-serif,system-ui,-apple-system,sans-serif}.seo-nav,.seo-footer,main{width:min(1120px,calc(100% - 40px));margin:auto}.seo-nav{min-height:72px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line)}.seo-nav nav{display:flex;flex-wrap:wrap;gap:18px}.seo-nav a,.seo-footer a,.seo-link-list a,.seo-article a{color:var(--text);text-decoration:none}.seo-nav nav a,.seo-footer a,.seo-article a:not(.seo-button){color:var(--accent)}.seo-brand{font-size:18px;font-weight:800;letter-spacing:-.03em}.seo-hero{isolation:isolate;max-width:820px;min-height:590px;padding:112px 0 92px;position:relative}.seo-hero-art{height:100%;inset:0 -260px auto -260px;mask-image:linear-gradient(90deg,#000 0%,#000 62%,transparent 100%);object-fit:cover;opacity:.55;pointer-events:none;position:absolute;transform:scaleX(-1);width:calc(100% + 520px);z-index:-2}.seo-hero::after{background:linear-gradient(90deg,rgba(9,9,11,.74) 0%,rgba(9,9,11,.42) 54%,rgba(9,9,11,.95) 100%);content:"";inset:0 -260px auto -260px;min-height:100%;position:absolute;z-index:-1}.seo-kicker{margin:0 0 12px;color:var(--accent);font:700 12px/1.2 ui-monospace,SFMono-Regular,Menlo,monospace;letter-spacing:.14em}.seo-hero h1,.seo-section h2,.seo-article h1,.seo-article h2{font-weight:800;letter-spacing:-.045em;line-height:1.06}.seo-hero h1{font-size:clamp(44px,8vw,88px);margin:0}.seo-lead{max-width:700px;color:#d5d5dc;font-size:clamp(18px,2.3vw,24px);margin:24px 0}.seo-actions{display:flex;gap:12px;flex-wrap:wrap}.seo-button{display:inline-flex;align-items:center;justify-content:center;background:var(--accent);color:#062419!important;border-radius:999px;padding:11px 18px;font-weight:800;text-decoration:none}.seo-button-secondary{background:transparent!important;border:1px solid var(--line);color:var(--text)!important}.seo-proof{color:var(--muted);font-size:13px;margin-top:18px}.seo-section{border-top:1px solid var(--line);padding:50px 0}.seo-section h2{font-size:clamp(27px,4vw,44px);margin:0 0 20px}.seo-split{display:grid;grid-template-columns:minmax(0,.85fr) minmax(0,1.15fr);gap:52px}.seo-list{margin:0;padding-left:20px;color:#d8d8de}.seo-list li+li{margin-top:10px}.seo-link-list{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:1px;background:var(--line);border:1px solid var(--line)}.seo-link-list a{background:var(--panel);padding:24px;transition:background .18s ease}.seo-link-list a:hover{background:#19342d}.seo-link-list strong,.seo-link-list span{display:block}.seo-link-list strong{font-size:17px;margin-bottom:7px}.seo-link-list span{color:var(--muted);font-size:14px;line-height:1.5}.seo-note{max-width:820px}.seo-footer{border-top:1px solid var(--line);color:var(--muted);font-size:13px;padding:28px 0 42px}.seo-article{width:min(820px,calc(100% - 40px));padding:46px 0 84px}.seo-crumb{display:flex;gap:8px;color:var(--muted);font-size:13px;margin-bottom:44px}.seo-article h1{font-size:clamp(38px,6vw,66px);margin:0 0 24px}.seo-answer{border-left:2px solid var(--accent);color:#e6e6e9;font-size:20px;line-height:1.58;margin:0 0 46px;padding-left:18px}.seo-article article>section{border-top:1px solid var(--line);padding:30px 0}.seo-article h2{font-size:27px;margin:0 0 12px}.seo-article p{color:#d4d4da}.seo-sources{padding-left:20px}.seo-sources li+li{margin-top:8px}@media(max-width:700px){.seo-nav{min-height:64px;gap:14px}.seo-nav nav{gap:11px;font-size:13px}.seo-hero{min-height:480px;padding:72px 0 60px}.seo-hero-art{inset:0 -20px auto -20px;width:calc(100% + 40px)}.seo-hero::after{inset:0 -20px auto -20px}.seo-section{padding:36px 0}.seo-split,.seo-link-list{grid-template-columns:1fr;gap:24px}.seo-link-list a{padding:20px}.seo-article{padding-top:30px}.seo-crumb{margin-bottom:28px}.seo-answer{font-size:18px}}

/* STH mascot visual system: editorial illustrations stay outside the calculator workspace. */
.seo-hero-art{inset:0 -320px auto -320px;mask-image:linear-gradient(90deg,#000 0%,#000 74%,transparent 100%);object-position:center;opacity:.92;transform:none;width:calc(100% + 640px)}
.seo-hero::after{background:linear-gradient(90deg,rgba(9,9,11,.42) 0%,rgba(9,9,11,.12) 46%,rgba(9,9,11,.88) 78%,rgba(9,9,11,.98) 100%);inset:0 -320px auto -320px}.seo-hero h1,.seo-hero .seo-lead,.seo-hero .seo-actions,.seo-hero .seo-proof,.seo-hero .seo-kicker{position:relative}.seo-hero .seo-lead{max-width:590px}
.seo-visual-story{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(280px,.9fr);align-items:center;gap:48px}.seo-visual-story-art,.seo-guide-visual,.seo-collection-visual{margin:0;overflow:hidden;border:1px solid rgba(52,211,153,.32);background:#06110f;border-radius:22px}.seo-visual-story-art img,.seo-guide-visual img,.seo-collection-visual img{display:block;width:100%;height:auto}.seo-visual-story p{color:#d4d4da;margin:0 0 20px}.seo-visual-story .seo-list{font-size:15px}
.seo-guide-visual{margin:0 0 44px;border-radius:20px}.seo-guide-visual img{aspect-ratio:16 / 7;object-fit:cover;object-position:center}.seo-collection-visual{margin:0 0 34px;max-height:260px}.seo-collection-visual img{aspect-ratio:16 / 6;object-fit:cover;object-position:center 42%}
.seo-footer{display:flex;align-items:center;justify-content:space-between;gap:20px}.seo-org-mark{display:block;width:96px;height:auto;opacity:.78}
@media (prefers-reduced-motion:no-preference){.seo-hero-art{animation:sth-mascot-float 9s ease-in-out infinite alternate}.seo-link-list a{transition:background .18s ease,transform .18s ease}.seo-link-list a:hover{transform:translateY(-3px)}}@keyframes sth-mascot-float{from{transform:translateY(0) scale(1)}to{transform:translateY(-8px) scale(1.012)}}
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.seo-guide-index{width:min(1120px,calc(100% - 40px))}.seo-guide-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:1px;background:var(--line);border:1px solid var(--line)}.seo-guide-grid a{background:var(--panel);color:var(--text);display:block;padding:0 24px 24px;text-decoration:none;transition:background .18s ease,transform .18s ease}.seo-guide-grid a:hover{background:#17342d;text-decoration:none}.seo-guide-grid img{display:block;width:calc(100% + 48px);aspect-ratio:16/8;object-fit:cover;margin:0 -24px 20px}.seo-guide-grid strong,.seo-guide-grid span{display:block}.seo-guide-grid strong{font-size:21px;line-height:1.15;letter-spacing:-.025em}.seo-guide-grid span{color:var(--muted);font-size:14px;line-height:1.55;margin-top:8px}.seo-mechanism{border-top:1px solid var(--line);display:grid;grid-template-columns:minmax(0,.92fr) minmax(280px,1.08fr);gap:34px;align-items:center;margin:22px 0 0;padding:34px 0}.seo-mechanism h2{font-size:clamp(26px,3.5vw,40px)!important}.seo-mechanism>img{border:1px solid rgba(52,211,153,.24);border-radius:18px;display:block;width:100%;height:auto}.seo-mini-grid,.seo-tier-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin:20px 0 0}.seo-tier-grid{grid-template-columns:repeat(3,minmax(0,1fr))}.seo-mini-grid div,.seo-tier-grid div{border-top:1px solid var(--line);padding-top:11px}.seo-mini-grid dt,.seo-tier-grid strong{color:var(--accent);display:block;font:700 12px/1.2 ui-monospace,SFMono-Regular,Menlo,monospace;letter-spacing:.06em;text-transform:uppercase}.seo-mini-grid dd,.seo-tier-grid span{color:#d4d4da;display:block;font-size:14px;line-height:1.45;margin:6px 0 0}.seo-formula{border-left:2px solid var(--accent);color:#e8fffa;display:flex;flex-direction:column;font:600 clamp(15px,2.1vw,22px)/1.45 ui-monospace,SFMono-Regular,Menlo,monospace;gap:3px;margin:22px 0 0;padding:16px 0 16px 18px;overflow-wrap:anywhere}.seo-formula b{color:var(--accent);font-size:14px}.seo-decision-tree{color:#d4d4da;counter-reset:tree;list-style:none;margin:20px 0 0;padding:0}.seo-decision-tree li{border-top:1px solid var(--line);counter-increment:tree;padding:11px 0 11px 34px;position:relative}.seo-decision-tree li::before{color:var(--accent);content:counter(tree);font:700 11px/22px ui-monospace,SFMono-Regular,Menlo,monospace;left:0;position:absolute;text-align:center;top:10px;width:22px}.seo-article article>.seo-mechanism+section{margin-top:0}@media(max-width:700px){.seo-guide-grid,.seo-mechanism{grid-template-columns:1fr}.seo-guide-grid a{padding:0 18px 20px}.seo-guide-grid img{width:calc(100% + 36px);margin:0 -18px 16px}.seo-tier-grid{grid-template-columns:1fr}.seo-mechanism{gap:20px;padding:28px 0}.seo-mechanism>img{order:-1}.seo-formula{font-size:14px}.seo-mini-grid{grid-template-columns:1fr}}
.seo-explainer-diagram{border:1px solid rgba(52,211,153,.36);border-radius:20px;margin:28px 0 0;overflow:hidden;background:#07100f}.seo-explainer-diagram figcaption{align-items:baseline;border-bottom:1px solid rgba(52,211,153,.18);display:flex;gap:12px;justify-content:space-between;padding:12px 16px}.seo-explainer-diagram figcaption span{color:var(--accent);font:700 11px/1.2 ui-monospace,SFMono-Regular,Menlo,monospace;letter-spacing:.08em;text-transform:uppercase}.seo-explainer-diagram figcaption small{color:var(--muted);font-size:12px}.seo-explainer-diagram img{display:block;height:auto;width:100%}@media(max-width:700px){.seo-explainer-diagram{border-radius:14px;margin-top:22px}.seo-explainer-diagram figcaption{align-items:flex-start;flex-direction:column;gap:4px;padding:10px 12px}}
.seo-runtime-compat ul{list-style:none;margin:20px 0 18px;padding:0}.seo-runtime-compat li{border-top:1px solid var(--line);display:grid;grid-template-columns:minmax(150px,.72fr) minmax(0,1.28fr);gap:18px;padding:12px 0}.seo-runtime-compat li:last-child{border-bottom:1px solid var(--line)}.seo-runtime-compat li strong{color:var(--accent);font:700 12px/1.35 ui-monospace,SFMono-Regular,Menlo,monospace;letter-spacing:.04em}.seo-runtime-compat li span{color:#d4d4da;line-height:1.5}.seo-runtime-compat p{border-left:2px solid var(--accent);font-size:15px;margin:0;padding-left:14px}.seo-runtime-compat p strong{color:#f2fff9}@media(max-width:700px){.seo-runtime-compat li{grid-template-columns:1fr;gap:3px}}
.seo-field-notes h3{font-size:16px;letter-spacing:-.015em;margin:30px 0 10px}.seo-field-notes p{max-width:720px}.seo-table-wrap{border:1px solid var(--line);margin:24px 0;overflow:auto}.seo-field-notes table{border-collapse:collapse;min-width:620px;width:100%}.seo-field-notes th,.seo-field-notes td{border-bottom:1px solid var(--line);padding:13px 14px;text-align:left;vertical-align:top}.seo-field-notes th{background:rgba(52,211,153,.08);color:#d8fff2;font:700 11px/1.35 ui-monospace,SFMono-Regular,Menlo,monospace;letter-spacing:.06em;text-transform:uppercase}.seo-field-notes td{color:#d4d4da;font-size:14px;line-height:1.55}.seo-field-notes tbody tr:last-child td{border-bottom:0}.seo-field-notes code,.seo-runtime-compat code{background:rgba(255,255,255,.07);border:1px solid rgba(255,255,255,.1);border-radius:4px;color:#e9fff7;font:500 .88em/1.25 ui-monospace,SFMono-Regular,Menlo,monospace;padding:.08em .32em}.seo-checklist{display:grid;gap:9px;list-style:none;margin:0;padding:0}.seo-checklist li{border-left:2px solid var(--accent);color:#d4d4da;padding-left:12px}.seo-code-example{background:#070b0d;border:1px solid rgba(52,211,153,.28);margin:24px 0 0}.seo-code-example figcaption{border-bottom:1px solid rgba(52,211,153,.2);color:var(--accent);font:700 11px/1.35 ui-monospace,SFMono-Regular,Menlo,monospace;letter-spacing:.06em;padding:10px 13px;text-transform:uppercase}.seo-code-example pre{margin:0;overflow:auto;padding:14px}.seo-code-example pre code{background:none;border:0;border-radius:0;color:#d9fff0;font:500 13px/1.55 ui-monospace,SFMono-Regular,Menlo,monospace;padding:0}@media(max-width:700px){.seo-field-notes h3{margin-top:26px}.seo-field-notes table{min-width:540px}.seo-field-notes th,.seo-field-notes td{padding:11px 12px}.seo-code-example pre{padding:12px}.seo-code-example pre code{font-size:12px}}