*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --bg:#f7f9fc;--surface:#fff;--surface-2:#f9fafb;--surface-3:#eff6ff;
  --border:#e5e7eb;--text:#111827;--muted:#4b5563;--dim:#6b7280;--soft:#9ca3af;
  --accent:#2563eb;--accent-dark:#1d4ed8;--accent-soft:#e0ecff;
  --success:#16a34a;--success-soft:#dcfce7;
  --warning:#d97706;--warning-soft:#fef3c7;
  --danger:#dc2626;--danger-soft:#fee2e2;
  --purple:#7c3aed;--purple-soft:#ede9fe;
  --teal:#0f766e;--teal-soft:#ccfbf1;
  --radius:18px;--shadow:0 10px 30px rgba(15,23,42,.04);
  --sans:Inter,Arial,sans-serif
}
html{scroll-behavior:smooth;overflow-x:hidden}
body{background:var(--bg);color:var(--text);font-family:var(--sans);
  font-size:15px;line-height:1.7;-webkit-font-smoothing:antialiased;overflow-x:hidden}
img,table,pre,iframe,video,canvas{max-width:100%}
a{color:var(--accent);text-decoration:none}
a:hover{color:var(--accent-dark)}
p{color:var(--muted);margin-bottom:13px}
strong{color:var(--text)}
ul,ol{color:var(--muted);padding-left:22px;margin:12px 0 16px}
li{margin-bottom:8px}
.hero,.article-hero,.hero-card,.content-card,.definition-card,
.content-stack,.layout,.article-card,.sidebar,.sidebar-card,
.related-card,.cta-block,.hub-cta,.calculator-callout,
.article-card,.formula-box,.table-wrap,.calc-shell,.result-card{max-width:100%;min-width:0}

.site-header{background:rgba(255,255,255,.94);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:20;backdrop-filter:blur(10px)}
.nav-wrap{max-width:1120px;margin:0 auto;padding:14px 20px;display:flex;align-items:center;justify-content:space-between;gap:18px}
.brand{display:flex;align-items:center;gap:10px;color:var(--text);font-weight:800;letter-spacing:-.03em;font-size:20px}
.brand:hover{color:var(--text)}
.brand-mark{width:34px;height:34px;border-radius:10px;background:linear-gradient(135deg,var(--accent),#60a5fa);display:grid;place-items:center;color:#fff;font-weight:800;box-shadow:0 10px 20px rgba(37,99,235,.18);flex:0 0 auto}
.top-nav{display:flex;align-items:center;gap:18px;font-size:14px;font-weight:600}
.top-nav a{color:var(--muted)}
.top-nav a:hover{color:var(--accent)}
.menu-btn{display:none;background:none;border:none;cursor:pointer;padding:8px;color:var(--text);border-radius:8px;line-height:1}

.mobile-nav{visibility:hidden;pointer-events:none;position:fixed;top:0;left:0;right:0;bottom:0;z-index:9999}
.mobile-nav.open{visibility:visible;pointer-events:auto}
.mobile-nav-overlay{position:absolute;top:0;left:0;right:0;bottom:0;background:rgba(15,23,42,.5)}
.mobile-nav-panel{position:absolute;top:0;right:0;width:280px;max-width:85vw;height:100%;background:#fff;box-shadow:-4px 0 24px rgba(15,23,42,.15);display:flex;flex-direction:column;overflow-y:auto;transform:translateX(100%);transition:transform .25s ease}
.mobile-nav.open .mobile-nav-panel{transform:translateX(0)}
.mobile-nav-head{display:flex;align-items:center;justify-content:space-between;padding:18px 20px;border-bottom:1px solid var(--border);background:#fff}
.mobile-nav-head strong{font-weight:800;font-size:16px;color:var(--text)}
.mobile-nav-close{background:none;border:none;cursor:pointer;color:var(--dim);padding:6px;border-radius:8px;line-height:1;font-size:22px}
.mobile-nav-links{flex:1}
.mobile-nav-links a{display:block;padding:15px 20px;font-size:15px;font-weight:600;color:var(--text);border-bottom:1px solid var(--border);text-decoration:none}
.mobile-nav-links a:active{background:var(--surface-2)}
.mobile-nav-footer{padding:16px 20px;border-top:1px solid var(--border);font-size:12px;color:var(--dim)}

.main{max-width:1120px;margin:0 auto;padding:20px 20px 70px}
.breadcrumb{display:flex;flex-wrap:wrap;align-items:center;gap:7px;color:var(--dim);font-size:13px;margin-bottom:18px}
.breadcrumb a{color:var(--dim);font-weight:600}
.breadcrumb a:hover{color:var(--accent)}

.hero-card{background:var(--surface);border:1px solid var(--border);border-radius:24px;box-shadow:var(--shadow);padding:22px 28px;position:relative;margin-bottom:20px;display:grid;grid-template-columns:minmax(0,1fr) 360px;gap:24px;align-items:center}
.eyebrow{display:inline-flex;align-items:center;padding:5px 10px;border-radius:999px;background:var(--accent-soft);color:var(--accent-dark);font-size:12px;font-weight:800;margin-bottom:10px}
h1,h2,h3{letter-spacing:-.035em;line-height:1.15;color:var(--text)}
h1{font-size:clamp(26px,3.8vw,42px);max-width:100%;margin-bottom:10px}
h2{font-size:clamp(22px,2.7vw,31px);margin:0 0 12px}
h3{font-size:19px;margin:22px 0 8px}
.hero-subtitle{font-size:15px;line-height:1.6;max-width:100%;color:var(--muted);margin:0}
.hero-actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:14px}
.pill{display:inline-flex;align-items:center;justify-content:center;min-height:32px;padding:5px 10px;border-radius:999px;background:#fff;border:1px solid var(--border);color:var(--muted);font-size:12.5px;font-weight:700}
.pill.blue{background:var(--accent-soft);border-color:#bfdbfe;color:var(--accent-dark)}
.pill.green{background:var(--success-soft);border-color:#bbf7d0;color:#166534}
.pill.warning{background:var(--warning-soft);border-color:#fde68a;color:#78350f}
.pill.purple{background:var(--purple-soft);border-color:#ddd6fe;color:#5b21b6}

.hero-search-panel{margin-top:0;max-width:480px;position:relative;z-index:100;background:var(--surface-2);border:1px solid var(--border);border-radius:18px;padding:16px}
.hero-search-label{font-size:11.5px;font-weight:700;color:var(--muted);letter-spacing:.04em;text-transform:uppercase;margin-bottom:8px;display:block}
.search-container{position:relative}
.search-input-wrap{position:relative}
.search-input{width:100%;padding:11px 14px 11px 40px;border-radius:12px;border:1px solid var(--border);background:#fff;color:var(--text);font-size:14px;font-family:var(--sans);outline:none;transition:border-color .15s ease,background .15s ease}
.search-input:focus{border-color:var(--accent);background:#fff}
.search-input::placeholder{color:var(--soft)}
.search-icon{position:absolute;left:12px;top:50%;transform:translateY(-50%);color:var(--soft);pointer-events:none}
.search-dropdown{position:absolute;left:0;right:0;top:calc(100% + 6px);background:var(--surface);border:1px solid var(--border);border-radius:14px;box-shadow:0 20px 40px rgba(15,23,42,.18);max-height:300px;overflow-y:auto;z-index:9999}
.search-dropdown.hidden{display:none}
.search-results{padding:4px 0}
.search-result{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:10px 14px;font-size:13.5px;color:var(--text);font-weight:600;border-bottom:1px solid var(--border);transition:background .1s ease;text-decoration:none;line-height:1.4}
.search-result:last-child{border-bottom:0}
.search-result:hover{background:var(--surface-2);text-decoration:none;color:var(--text)}
.search-cat{font-size:11px;font-weight:700;color:var(--dim);background:var(--surface-2);padding:2px 7px;border-radius:999px;white-space:nowrap;flex-shrink:0}
.search-empty{padding:12px 14px;font-size:13.5px;color:var(--dim)}

.layout{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:24px;align-items:start}
.content-stack{display:grid;gap:24px}
.content-card,.sidebar-card,.article-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);min-width:0;max-width:100%;overflow-wrap:break-word;word-wrap:break-word}
.content-card{padding:24px}
.sidebar{position:sticky;top:84px;display:grid;gap:16px}
.sidebar-card{padding:18px}
.sidebar-card h2{font-size:18px;margin-bottom:10px}
.toc{display:grid;gap:8px;font-size:14px}
.toc a{color:var(--muted);font-weight:600;padding:8px 9px;border-radius:10px}
.toc a:hover{background:var(--surface-3);color:var(--accent)}
.toc-select{display:none;width:100%;padding:10px 12px;border:1px solid var(--border);border-radius:12px;background:#fff;color:var(--text);font-size:14px;font-weight:600;cursor:pointer}
.sidebar-cta{background:var(--accent-soft);border-color:#bfdbfe}
.sidebar-cta p{font-size:14px;margin-bottom:12px}

.related-guide-nav,.also-useful-nav,.quick-links-nav{display:flex;flex-direction:column;gap:0}
.related-guide-nav a,.also-useful-nav a,.quick-links-nav a{display:block;padding:10px 0;font-size:14px;font-weight:600;color:var(--text);border-bottom:1px solid var(--border);text-decoration:none;line-height:1.4}
.related-guide-nav a:last-child,.also-useful-nav a:last-child,.quick-links-nav a:last-child{border-bottom:0}
.related-guide-nav a:hover,.also-useful-nav a:hover,.quick-links-nav a:hover{color:var(--accent);text-decoration:none}
.related-sidebar-mobile,.also-useful-sidebar-mobile,.quick-links-sidebar-mobile{display:none;padding:0 12px 24px;box-sizing:border-box;width:100%}

.calc-shell{display:grid;grid-template-columns:minmax(0,1fr) 320px;gap:18px;align-items:start}
.calc-panel{background:var(--surface-2);border:1px solid var(--border);border-radius:18px;padding:18px}
.field-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;margin-top:12px}
.field{display:grid;gap:6px}
label{font-size:13px;font-weight:800;color:var(--text)}
.field small{color:var(--dim);font-size:12px;line-height:1.35}
input,select{width:100%;border:1px solid var(--border);border-radius:12px;padding:11px 12px;background:#fff;color:var(--text);font-family:var(--sans);font-size:14px;outline:none}
input:focus,select:focus{border-color:var(--accent);box-shadow:0 0 0 3px rgba(37,99,235,.12)}
.error-box{display:none;border:1px solid #fecaca;background:var(--danger-soft);color:#7f1d1d;border-radius:14px;padding:12px 14px;margin-top:14px;font-size:13.5px;font-weight:700}
.error-box.show{display:block}
.warning-box{display:none;border:1px solid #fde68a;background:var(--warning-soft);color:#78350f;border-radius:14px;padding:12px 14px;margin-top:14px;font-size:13.5px;font-weight:700}
.warning-box.show{display:block}
.result-stack{display:grid;gap:12px}
.result-card{border:1px solid var(--border);border-radius:16px;background:#fff;padding:14px}
.result-card.primary{border-color:#bfdbfe;background:linear-gradient(180deg,#fff,var(--surface-3))}
.result-label{display:block;font-size:12px;font-weight:800;color:var(--dim);text-transform:uppercase;letter-spacing:.06em;margin-bottom:3px}
.result-value{font-size:26px;font-weight:800;letter-spacing:-.04em;color:var(--text)}
.result-note{font-size:12.5px;color:var(--dim);margin-top:2px}
.assumption-list{display:grid;gap:7px;margin-top:12px;color:var(--muted);font-size:13.5px}
.assumption-list span{display:flex;justify-content:space-between;gap:10px;border-top:1px solid var(--border);padding-top:7px}
.assumption-list strong{white-space:nowrap}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:44px;padding:11px 16px;border-radius:999px;border:1px solid transparent;font-weight:800;font-size:14px;text-decoration:none;white-space:nowrap;transition:transform .15s ease;cursor:pointer;font-family:var(--sans)}
.btn:hover{text-decoration:none;transform:translateY(-1px)}
.btn-primary{background:var(--accent);color:#fff;box-shadow:0 12px 24px rgba(37,99,235,.2)}
.btn-primary:hover{background:var(--accent-dark);color:#fff}
.btn-secondary{border-color:var(--border);background:#fff;color:var(--text)}
.btn-secondary:hover{color:var(--accent);border-color:#bfdbfe;background:var(--surface-3)}
.calculator-actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:16px}
.calculator-callout,.cta-block{border:1px solid #bfdbfe;background:linear-gradient(180deg,#fff,var(--surface-3));border-radius:16px;padding:18px;margin:16px 0;display:grid;grid-template-columns:minmax(0,1fr) auto;gap:16px;align-items:center;overflow:hidden}
.calculator-callout p,.cta-block p{margin-bottom:0}
.cta-disclosure{font-size:12px;color:var(--dim);margin-top:8px}
.formula-box{background:#0f172a;color:#e5e7eb;padding:16px;border-radius:14px;overflow-x:auto;max-width:100%;font-size:14px;line-height:1.7;margin:16px 0}
.formula-box code{display:block;max-width:100%;white-space:pre;font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,"Liberation Mono","Courier New",monospace}
.callout{border:1px solid #bfdbfe;background:var(--surface-3);border-radius:16px;padding:18px;margin:16px 0}
.callout.warning{border-color:#fde68a;background:var(--warning-soft)}
.table-wrap{width:100%;max-width:100%;overflow-x:auto;margin:16px 0;border:1px solid var(--border);border-radius:14px;background:#fff}
table{width:100%;border-collapse:collapse;min-width:680px;font-size:14px}
th,td{padding:12px 13px;border-bottom:1px solid var(--border);text-align:left;vertical-align:top}
th{background:var(--surface-2);color:var(--text);font-weight:800}
td{color:var(--muted)}
tr:last-child td{border-bottom:0}
.related-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin-top:16px}
.related-card{background:var(--surface-2);border:1px solid var(--border);border-radius:14px;padding:16px;min-width:0;overflow-wrap:break-word}
.related-card h3{font-size:17px;margin:0 0 7px}
.related-card p{font-size:14px;margin-bottom:10px}
.link-arrow{font-weight:800;font-size:14px}
.faq-item{border-top:1px solid var(--border);padding-top:16px;margin-top:16px}
.faq-item h3{margin:0 0 6px;font-size:17px}
.glossary-pills{display:flex;flex-wrap:wrap;gap:9px;margin-top:14px}
.glossary-pill{display:inline-flex;align-items:center;min-height:36px;padding:7px 12px;border-radius:999px;border:1px solid #bfdbfe;background:var(--accent-soft);color:var(--accent-dark);font-size:13px;font-weight:800}
.glossary-pill:hover{background:#dbeafe;color:var(--accent-dark)}
.footer{border-top:1px solid var(--border);background:#fff;padding:40px 20px 24px;margin-top:40px}
.footer-inner{max-width:1120px;margin:0 auto}
.footer-cols{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:32px;margin-bottom:32px}
.footer-col h4{font-size:11px;font-weight:800;letter-spacing:.08em;text-transform:uppercase;color:var(--dim);margin-bottom:12px}
.footer-col ul{list-style:none;display:flex;flex-direction:column;gap:8px;padding:0;margin:0}
.footer-col ul li{margin:0}
.footer-col ul li a{color:var(--muted);font-size:13px;font-weight:600;transition:color .12s ease}
.footer-col ul li a:hover{color:var(--accent);text-decoration:none}
.footer-base{border-top:1px solid var(--border);padding-top:20px;color:var(--dim);font-size:12px}

@media(max-width:980px){
  .hero-card{grid-template-columns:1fr}
  .layout{display:flex;flex-direction:column}
  .sidebar{position:static;order:-1;width:100%}
  .toc{display:none}
  .toc-select{display:block}
  .calc-shell{grid-template-columns:1fr}
  .related-grid{grid-template-columns:repeat(2,minmax(0,1fr))}
  .related-sidebar,.also-useful-sidebar,.quick-links-sidebar{display:none}
  .related-sidebar-mobile,.also-useful-sidebar-mobile,.quick-links-sidebar-mobile{display:block}
}
@media(max-width:760px){
  .top-nav{display:none}
  .menu-btn{display:block}
  .main{padding:16px 12px 48px}
  .hero,.article-hero,.hero-card{padding:16px}
  .content-card,.definition-card,.article-card{padding:16px}
  .sidebar-card{padding:14px}
  .cta-block,.hub-cta{padding:16px}
  h1{font-size:22px}
  h2{font-size:19px;margin-bottom:10px}
  h3{font-size:16px}
  .hero-subtitle{font-size:14px}
  .hero-search-panel{max-width:100%}
  .field-grid{grid-template-columns:1fr}
  .calculator-callout{display:block}
  .calculator-callout .btn{margin-top:12px;display:block;text-align:center}
  .cta-block{grid-template-columns:1fr}
  .btn{width:100%;box-sizing:border-box}
  .calculator-actions{display:grid}
  .related-grid{grid-template-columns:1fr}
  .cta-block p,.hub-cta p{max-width:100%}
  .footer-cols{grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
}
@media(max-width:420px){.footer-cols{grid-template-columns:1fr}}