*,*::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}

    a{color:var(--accent);text-decoration:none}
    a:hover{color:var(--accent-dark);text-decoration:underline}
    p{color:var(--muted);margin-bottom:13px}
    ul,ol{color:var(--muted);padding-left:22px;margin:12px 0 16px}
    li{margin-bottom:8px}
    strong{color:var(--text)}

    .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{
      background:var(--surface);
      border:1px solid var(--border);
      border-radius:24px;
      box-shadow:var(--shadow);
      padding:22px 28px;
      margin-bottom:20px;
      position:relative;
    }

    .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:700;
      margin-bottom:10px;
    }

    h1,h2,h3{
      letter-spacing:-.035em;
      line-height:1.15;
      color:var(--text);
    }

    h1{
      font-size:clamp(24px,3.4vw,38px);
      max-width:100%;
      margin-bottom:10px;
    }

    h2{
      font-size:clamp(25px,3vw,34px);
      margin:0 0 12px;
    }

    h3{
      font-size:21px;
      margin:22px 0 8px;
    }

    .hero-subtitle{
      color:var(--muted);
      font-size:15px;
      line-height:1.6;
      max-width:100%;
    }

    .meta-row{
      display:flex;
      flex-wrap:wrap;
      gap:9px;
      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.warning{
      background:var(--warning-soft);
      border-color:#fde68a;
      color:#78350f;
    }

    .pill.green{
      background:var(--success-soft);
      border-color:#bbf7d0;
      color:#166534;
    }

    .layout{
      display:grid;
      grid-template-columns:minmax(0,1fr) 300px;
      gap:24px;
      align-items:start;
    }

    .content-stack{
      display:grid;
      gap:24px;
      min-width:0;
      max-width:100%;
      overflow:hidden;
    }

    .content-card,
    .definition-card,
    .sidebar-card{
      background:var(--surface);
      border:1px solid var(--border);
      border-radius:var(--radius);
      box-shadow:var(--shadow);
    }

    .content-card,
    .definition-card{
      padding:28px;
      min-width:0;
      max-width:100%;
      overflow-wrap:break-word;
      word-wrap:break-word;
    }

    .definition-card{
      background:linear-gradient(180deg,#fff,var(--surface-3));
      border-color:#bfdbfe;
    }

    .definition-label{
      color:var(--accent-dark);
      font-size:13px;
      font-weight:800;
      text-transform:uppercase;
      letter-spacing:.05em;
      margin-bottom:8px;
    }

    .definition-text{
      color:var(--text);
      font-size:22px;
      line-height:1.55;
      font-weight:700;
      letter-spacing:-.02em;
      margin:0;
    }

    .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:620px;
      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}

    .example-grid{
      display:grid;
      grid-template-columns:repeat(3,minmax(0,1fr));
      gap:14px;
      margin-top:16px;
    }

    .example-card{
      background:var(--surface-2);
      border:1px solid var(--border);
      border-radius:14px;
      padding:16px;
    }

    .example-card strong{
      display:block;
      color:var(--text);
      font-size:18px;
      margin-bottom:4px;
    }

    .example-card span{
      color:var(--muted);
      font-size:14px;
    }

    .formula-box{
      background:#0f172a;
      color:#e5e7eb;
      padding:16px;
      border-radius:14px;
      font-size:14px;
      line-height:1.7;
      margin:16px 0;
    }

    .formula-box p{
      color:#e5e7eb;
      margin:0;
    }

    .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);
    }

    .calculator-callout{
      display:grid;
      grid-template-columns:minmax(0,1fr) auto;
      gap:16px;
      align-items:center;
      border:1px solid #bfdbfe;
      background:linear-gradient(180deg,#fff,var(--surface-3));
      border-radius:var(--radius);
      padding:20px;
      overflow:hidden;
    }

    .calculator-callout h2{
      font-size:24px;
      margin-bottom:6px;
    }

    .calculator-callout p{margin:0}

    .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,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;
    }

    .related-grid{
      display:grid;
      grid-template-columns:repeat(2,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:18px;
      margin:0 0 7px;
    }

    .related-card p{
      font-size:14px;
      margin-bottom:10px;
    }

    .link-arrow{
      font-weight:800;
      font-size:14px;
    }

    .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);
      text-decoration:none;
    }

    .sidebar-cta{
      background:var(--accent-soft);
      border-color:#bfdbfe;
    }

    .sidebar-cta p{
      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}}
    .hero-search-panel{margin-top:14px;max-width:480px;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;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: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)}

    .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}
    .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){
      .layout{display:flex;flex-direction:column}
      .sidebar{position:static;order:-1;width:100%}
      .example-grid{grid-template-columns:1fr}
    }
    @media (max-width:760px){
      .top-nav{display:none}
      .main{padding:16px 12px 48px}
      .hero{padding:16px}
      .content-card,.definition-card{padding:16px}
      .sidebar-card{padding:14px}
      h1{font-size:22px}
      h2{font-size:19px;margin-bottom:10px}
      h3{font-size:16px}
      .hero-subtitle{font-size:14px}
      .calculator-callout{display:block}
      .calculator-callout .btn{margin-top:12px;display:block;text-align:center}
      .btn{width:100%;box-sizing:border-box}
      .related-grid{grid-template-columns:1fr}
      .hero-search-panel{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}
    }
    /* ── Universal overflow fix ── */
    img,table,pre,iframe,video,canvas{max-width:100%}
    .hero,.content-card,.definition-card,.content-stack,.layout,
    .sidebar,.sidebar-card,.related-card,.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}
    }