*,*::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}
body{background:var(--bg);color:var(--text);font-family:var(--sans);
  font-size:15px;line-height:1.7;-webkit-font-smoothing:antialiased}

    a{color:var(--accent);text-decoration:none}
    a:hover{color:var(--accent-dark);text-decoration:underline}
    button,input,select{font:inherit}
    .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-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)}
    .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)}
    .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)}
    .breadcrumb a:hover{color:var(--accent)}
    .hero{display:grid;grid-template-columns:minmax(0,1.18fr) minmax(280px,.82fr);gap:20px;align-items:stretch;margin-bottom:20px}
    .hero-card,.calculator-shell,.content-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow)}
    .hero-card{padding:22px 28px;position:relative}
    .eyebrow{display:inline-flex;align-items:center;gap:8px;padding:5px 10px;border-radius:999px;background:var(--accent-soft);color:var(--accent-dark);font-size:12px;font-weight:700;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:780px;margin-bottom:10px;position:relative;z-index:1}
    .hero-subtitle{color:var(--muted);font-size:15px;line-height:1.6;max-width:720px;position:relative;z-index:1}
    .hero-actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:14px;position:relative;z-index:1}
    .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;cursor:pointer;text-decoration:none;transition:transform .15s ease,box-shadow .15s ease,background .15s ease}
    .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{background:var(--surface);color:var(--accent);border-color:var(--border)}
    .btn-secondary:hover{background:var(--surface-3);color:var(--accent-dark)}
    .hero-search-panel{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);padding:20px 22px;display:flex;flex-direction:column;justify-content:center;gap:14px;position:relative;z-index:100}
    .hero-search-label{font-size:11.5px;font-weight:700;color:var(--muted);letter-spacing:.04em;text-transform:uppercase;margin-bottom:8px}
    .trust-mini{display:grid;gap:8px;list-style:none;margin-top:6px}
    .trust-mini li{display:flex;gap:8px;align-items:flex-start;color:var(--muted);font-size:12.5px}
    .tick{width:20px;height:20px;min-width:20px;display:grid;place-items:center;border-radius:999px;background:var(--success-soft);color:var(--success);font-weight:800;font-size:11px}
    .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:var(--surface-2);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}
    .page-stack{display:grid;gap:24px}
    .calculator-shell{overflow:hidden}
    .calculator-header{padding:24px;border-bottom:1px solid var(--border);display:flex;justify-content:space-between;gap:18px;align-items:flex-start;background:linear-gradient(180deg,#fff,var(--surface-2))}
    .calculator-header h2{font-size:26px;margin-bottom:8px}
    .calculator-header p{color:var(--muted);max-width:680px}
    .calculator-grid{display:grid;grid-template-columns:minmax(0,.9fr) minmax(300px,1.1fr);gap:0}
    .inputs-panel{padding:24px;border-right:1px solid var(--border);background:var(--surface)}
    .results-panel{padding:24px;background:var(--surface-2)}
    .form-grid{display:grid;gap:16px}
    .field label{display:flex;justify-content:space-between;align-items:center;gap:10px;color:var(--text);font-weight:700;font-size:14px;margin-bottom:7px}
    .hint{color:var(--dim);font-size:12px;font-weight:600}
    .input-wrap{position:relative}
    .prefix,.suffix{position:absolute;top:50%;transform:translateY(-50%);color:var(--dim);font-weight:700;pointer-events:none}
    .prefix{left:13px}
    .suffix{right:13px}
    input,select{width:100%;min-height:46px;border:1px solid var(--border);border-radius:12px;background:#fff;color:var(--text);padding:11px 13px;outline:none;transition:border .15s ease,box-shadow .15s ease}
    input.with-prefix{padding-left:32px}
    input.with-suffix{padding-right:42px}
    input:focus,select:focus{border-color:var(--accent);box-shadow:0 0 0 4px var(--accent-soft)}
    .help-text{color:var(--dim);font-size:13px;margin-top:6px}
    .use-box{margin-top:20px;background:var(--surface-3);border:1px solid #bfdbfe;border-radius:14px;padding:16px}
    .use-box h3{font-size:17px;margin-bottom:8px}
    .use-box ol{padding-left:20px;color:var(--muted);display:grid;gap:5px;font-size:14px}
    .formula-box{margin-top:16px;background:#fff;border:1px solid var(--border);border-radius:14px;padding:16px}
    .formula-box h3{font-size:17px;margin-bottom:8px}
    .formula{background:#0f172a;color:#e5e7eb;padding:13px;border-radius:12px;overflow:auto;font-size:13px;line-height:1.6;margin-bottom:10px}
    .formula code{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,"Liberation Mono","Courier New",monospace;white-space:pre}
    .error-box{display:none;margin-bottom:14px;background:var(--danger-soft);border:1px solid #fecaca;color:#991b1b;border-radius:14px;padding:13px;font-size:14px;font-weight:600}
    .result-grid{display:grid;gap:14px}
    .result-card{background:#fff;border:1px solid var(--border);border-radius:16px;padding:16px}
    .result-card.primary{border-color:#bfdbfe;background:linear-gradient(180deg,#fff,var(--surface-3))}
    .result-label{color:var(--dim);font-size:13px;font-weight:700;margin-bottom:3px}
    .result-value{font-size:clamp(24px,4vw,34px);font-weight:800;line-height:1.1;letter-spacing:-.04em;color:var(--text)}
    .result-card:not(.primary) .result-value{font-size:24px}
    .result-explain{color:var(--muted);font-size:13px;margin-top:7px}
    .pill-row{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px}
    .pill{display:inline-flex;align-items:center;justify-content:center;min-height:34px;padding:6px 11px;border-radius:999px;background:#fff;border:1px solid var(--border);color:var(--muted);font-size:13px;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}
    .result-warning{margin-top:14px;border-radius:14px;border:1px solid #fde68a;background:var(--warning-soft);color:#78350f;padding:13px;font-size:13px;font-weight:600}
    .cta-block{background:linear-gradient(135deg,#0f172a,#1e3a8a);border-radius:var(--radius);padding:26px;color:#fff;box-shadow:0 20px 40px rgba(15,23,42,.14)}
    .cta-block h2{color:#fff;font-size:26px;margin-bottom:8px}
    .cta-block p{color:#dbeafe;margin-bottom:16px;max-width:760px}
    .cta-block .btn{background:#fff;color:var(--accent-dark)}
    .cta-block .btn:hover{background:#eff6ff;color:var(--accent-dark)}
    .disclosure{margin-top:12px;color:#bfdbfe;font-size:13px}
    .content-card{padding:26px}
    .content-card h2{font-size:28px;margin-bottom:12px}
    .content-card h3{font-size:20px;margin:22px 0 8px}
    .content-card p{color:var(--muted);margin-bottom:12px}
    .content-card ul{padding-left:21px;color:var(--muted);margin:10px 0 0}
    .content-card li{margin-bottom:8px}
    .info-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin-top:16px}
    .mini-card{background:var(--surface-2);border:1px solid var(--border);border-radius:14px;padding:15px}
    .mini-card h3{font-size:17px;margin:0 0 6px}
    .mini-card p{font-size:14px;margin:0 0 10px}
    .link-arrow{font-weight:800;font-size:14px}
    .callout{border:1px solid #bfdbfe;background:var(--surface-3);border-radius:14px;padding:16px;margin:16px 0}
    .callout.warning{border-color:#fde68a;background:var(--warning-soft)}
    .callout strong{color:var(--accent-dark)}
    .callout.warning strong{color:#78350f}
    .faq-list{display:grid;gap:12px;margin-top:14px}
    details{background:var(--surface-2);border:1px solid var(--border);border-radius:14px;padding:15px 16px}
    summary{cursor:pointer;font-weight:800;color:var(--text);line-height:1.35}
    details p{margin:10px 0 0;color:var(--muted)}
    .sidebar{position:sticky;top:84px;display:grid;gap:16px}
    .sidebar-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow);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);text-decoration:none}
    .sidebar-cta{background:var(--accent-soft);border-color:#bfdbfe}
    .sidebar-cta p{color:var(--muted);font-size:14px;margin-bottom:12px}
    .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}
    @media(max-width:980px){.toc{display:none}.toc-select{display:block}}
    .footer{border-top:1px solid var(--border);background:#fff;padding:40px 20px 24px}
    .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}
    .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:720px){.footer-cols{grid-template-columns:repeat(2,minmax(0,1fr));gap:24px}}
    @media(max-width:420px){.footer-cols{grid-template-columns:1fr}}
    @media (max-width:980px){
      .hero,.layout,.calculator-grid{grid-template-columns:1fr}
      .inputs-panel{border-right:0;border-bottom:1px solid var(--border)}
      .sidebar{position:static;order:-1}
      .info-grid{grid-template-columns:1fr}
    }
    @media (max-width:720px){
      .top-nav{display:none}
      .main{padding:24px 14px 54px}
      .hero-card,.calculator-header,.inputs-panel,.results-panel,.content-card,.cta-block{padding:18px}
      .hero-search-panel{padding:16px 18px}
      .calculator-header{display:block}
      .hero-actions{flex-direction:column}
      .btn{width:100%}
      h1{font-size:28px}
      .hero-subtitle{font-size:14px}
      .result-value{font-size:30px}
    }

    /* ── Mobile overflow fix ── */
    *{box-sizing:border-box}
    img,table,pre,iframe,video,canvas{max-width:100%}
    .hero,.hero-card,.content-card,.definition-card,.content-stack,.layout,
    .article-card,.sidebar,.sidebar-card,.calculator-shell,.related-card,
    .cta-block,.hub-cta,.calculator-callout{max-width:100%;min-width:0}

    /* ── Mobile hamburger menu ── */
    .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);
    }
    @media(max-width:760px){
      .top-nav{display:none}
      .menu-btn{display:block}
    }