:root{--bg: #f4f6fa;--card: #ffffff;--ink: #101828;--ink-soft: #5b6474;--line: #e3e8f0;--sidebar-bg: #0e1726;--sidebar-ink: #e6ebf4;--sidebar-soft: #8b97ab;--accent: #16a34a;--radius: 12px;--shadow: 0 1px 2px rgb(16 24 40 / .05), 0 4px 16px rgb(16 24 40 / .06)}*{box-sizing:border-box}body{margin:0;font-family:Segoe UI,system-ui,-apple-system,Helvetica Neue,Arial,sans-serif;background:var(--bg);color:var(--ink);line-height:1.5}.app-shell{display:flex;min-height:100vh}.app-main{flex:1;min-width:0}.page{max-width:1040px;margin:0 auto;padding:40px 32px 64px}.ad-rail{--ad-slot-w: 300px;--ad-slot-h: 600px;width:calc(var(--ad-slot-w) + 32px);flex-shrink:0;border-left:1px solid var(--line);background:#eef1f6}.ad-rail-inner{position:sticky;top:0;padding:40px 16px 24px}.ad-slot{display:flex;justify-content:center}.ad-placeholder{width:var(--ad-slot-w);height:var(--ad-slot-h);display:flex;flex-direction:column;align-items:center;justify-content:center;gap:6px;border:1px dashed 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#a78bfa}.book-thumb{width:42px;border-radius:4px;border:1px solid rgb(255 255 255 / .18);box-shadow:0 2px 8px #00000073;flex-shrink:0}.book-link-text{display:flex;flex-direction:column;gap:2px;min-width:0}.book-link:hover{background:#ffffff0f}.book-link.active{background:#ffffff1a;border-left-color:var(--book-accent)}.book-num{font-size:11px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--book-accent)}.book-title{font-weight:600;font-size:15px}.book-meta{display:flex;gap:8px;align-items:baseline;font-size:12px;color:var(--sidebar-soft)}.sidebar-foot{display:flex;flex-direction:column;gap:4px;padding:14px 10px 4px;border-top:1px solid rgb(255 255 255 / .08);font-size:11.5px;color:var(--sidebar-soft)}.eyebrow{font-size:12px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--accent);margin-bottom:6px}.muted{color:var(--ink-soft)}.error-box{background:#fef2f2;border:1px solid #fecaca;color:#b91c1c;border-radius:var(--radius);padding:14px 18px;margin-bottom:24px}.error-box code{background:#0000000f;padding:1px 6px;border-radius:4px}.night-sky,.home-hero,.book-banner{background-image:radial-gradient(1px 1px at 22px 34px,rgb(255 255 255 / .55) 50%,transparent 51%),radial-gradient(1px 1px at 88px 12px,rgb(255 255 255 / .35) 50%,transparent 51%),radial-gradient(1.5px 1.5px at 140px 64px,rgb(255 255 255 / .45) 50%,transparent 51%),radial-gradient(ellipse at 65% 30%,rgb(255 255 255 / .09),transparent 55%),linear-gradient(150deg,var(--grad-from, #0e1726),var(--grad-to, #1c2c4a));background-size:180px 120px,180px 120px,180px 120px,cover,cover;color:#fff;border-radius:16px}.home-hero{margin-bottom:32px;padding:36px 36px 32px;--grad-from: #0a1626;--grad-to: #14395c}.home-hero .eyebrow{color:#7ef0b2}.home-hero h1{margin:0 0 10px;font-size:34px;line-height:1.2;color:#f5eea6;letter-spacing:.01em}.home-hero p{color:#ffffffd9;font-size:16px;margin:0;max-width:620px}.home-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}@media(max-width:900px){.home-grid{grid-template-columns:repeat(2,1fr)}}@media(max-width:620px){.home-grid{grid-template-columns:1fr}}.home-card{display:flex;flex-direction:column;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);overflow:hidden;text-decoration:none;color:inherit;transition:transform .12s ease,box-shadow .12s ease}.home-card:hover{transform:translateY(-3px);box-shadow:0 4px 8px #10182814,0 14px 32px #10182824}.home-cover-wrap{background:#0b1220}.home-cover{display:block;width:100%;height:auto}.home-card-body{display:flex;flex-direction:column;flex:1;padding:18px 20px 20px}.home-card h2{margin:0 0 8px;font-size:21px}.home-card p{color:var(--ink-soft);font-size:14px;margin:0 0 16px;flex:1}.home-card-foot{font-size:13px;font-weight:600;color:var(--accent)}.book-banner{display:flex;align-items:center;gap:28px;padding:28px 32px;margin-bottom:28px;box-shadow:0 8px 28px #080f1e47}.book-banner-text{flex:1;min-width:0}.banner-eyebrow{font-size:12px;font-weight:700;letter-spacing:.14em;text-transform:uppercase;color:var(--header-ink);margin-bottom:8px}.book-banner h1{margin:0 0 12px;font-size:32px;line-height:1.15;color:var(--title-ink, #f5eea6);letter-spacing:.02em;text-shadow:0 2px 12px rgb(0 0 0 / .35)}.banner-badges{display:flex;align-items:center;gap:14px;flex-wrap:wrap;margin-bottom:12px}.level-pill{display:inline-block;background:var(--pill-bg);color:var(--pill-text);border:2px solid rgb(255 255 255 / .75);border-radius:999px;padding:4px 16px;font-size:12.5px;font-weight:800;letter-spacing:.12em;text-transform:uppercase}.banner-motto{font-size:12px;font-weight:700;letter-spacing:.14em;text-transform:uppercase;color:var(--header-ink)}.book-banner 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20px;font-size:14px}.chapter-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:16px}.chapter-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:16px 18px;display:flex;flex-direction:column;gap:4px}.chapter-card.has-calc{cursor:pointer;border-color:color-mix(in srgb,var(--accent) 35%,var(--line));box-shadow:var(--shadow);transition:transform .12s ease}.chapter-card.has-calc:hover{transform:translateY(-2px)}.chapter-num{font-size:11px;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--ink-soft)}.chapter-title{font-weight:700;font-size:15px}.chapter-focus{font-size:13px;color:var(--ink-soft);flex:1}.chapter-badge{margin-top:10px;font-size:12.5px;font-weight:600;color:var(--ink-soft)}.chapter-badge.on{color:var(--accent)}.chapter-head{margin-bottom:18px}.chapter-head 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0}.adorn{color:var(--ink-soft);font-size:14px;font-weight:600;white-space:nowrap}.field-help{font-size:12.5px;color:var(--ink-soft)}.reset-btn{align-self:flex-start;margin-top:4px;-webkit-appearance:none;-moz-appearance:none;appearance:none;border:1.5px solid var(--line);background:var(--card);color:var(--ink-soft);font:inherit;font-size:13.5px;font-weight:600;border-radius:999px;padding:8px 16px;cursor:pointer;transition:border-color .12s ease,color .12s ease}.reset-btn:hover:not(:disabled){border-color:var(--accent);color:var(--accent)}.reset-btn:disabled{opacity:.45;cursor:default}.result{display:flex;flex-direction:column;gap:2px}.result-label{font-size:13.5px;color:var(--ink-soft);font-weight:600}.result-value{font-size:22px;font-weight:700;font-variant-numeric:tabular-nums}.result.primary .result-value{font-size:34px;color:var(--accent)}.formula-box{margin-top:auto;padding-top:16px;border-top:1px dashed color-mix(in srgb,var(--accent) 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