:root{
  --bg:#f7f5ff;--surface:#fff;--text:#172033;--muted:#667085;
  --primary:#7c3aed;--primary-dark:#6d28d9;--border:#e5e7eb;
  --success:#15803d;--shadow:0 8px 30px rgba(15,23,42,.07);
  --radius:16px;--max:1180px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:Inter,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;background:var(--bg);color:var(--text);line-height:1.65}
a{color:inherit;text-decoration:none}
.container{width:min(calc(100% - 32px),var(--max));margin:auto}
header{background:#fff;border-bottom:1px solid var(--border);position:sticky;top:0;z-index:20}
.nav{height:68px;display:flex;align-items:center;justify-content:space-between;gap:20px}
.logo{font-weight:900;font-size:21px;color:var(--primary);letter-spacing:-.5px}
.navlinks{display:flex;gap:18px;align-items:center}
.navlinks a{font-weight:700;font-size:14px;color:#344054}
.menu-btn{display:none;border:1px solid var(--border);background:#fff;border-radius:10px;padding:9px 11px;font-size:18px}
.hero{padding:54px 0 35px;text-align:center}
.hero h1{font-size:clamp(30px,5vw,48px);line-height:1.1;margin:0 0 14px;letter-spacing:-1.4px}
.hero p{max-width:720px;margin:0 auto;color:var(--muted);font-size:17px}
.search{max-width:650px;margin:25px auto 0;display:flex;background:#fff;border:1px solid var(--border);border-radius:14px;padding:6px;box-shadow:var(--shadow)}
.search input{flex:1;border:0;outline:0;padding:12px;font-size:15px;background:transparent}
.btn{border:0;border-radius:11px;padding:12px 18px;background:var(--primary);color:#fff;font-weight:800;cursor:pointer}
.btn:hover{background:var(--primary-dark)}
.section{padding:26px 0}
.section-title{display:flex;justify-content:space-between;align-items:center;margin-bottom:15px}
.section-title h2{font-size:24px;margin:0}
.grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:20px;box-shadow:var(--shadow);transition:.2s}
.card:hover{transform:translateY(-2px);border-color:#c7d2fe}
.card-icon{font-size:27px;margin-bottom:10px}
.card h3{margin:0 0 6px;font-size:17px}
.card p{margin:0;color:var(--muted);font-size:14px}
.ad-slot{min-height:110px;border:1px dashed #cbd5e1;background:#fff;border-radius:14px;display:flex;align-items:center;justify-content:center;color:#94a3b8;font-size:12px;margin:25px 0}
.tool-wrap{max-width:780px;margin:0 auto;padding:35px 0}
.breadcrumb{font-size:13px;color:var(--muted);margin-bottom:15px}
.tool-card{background:#fff;border:1px solid var(--border);border-radius:20px;padding:25px;box-shadow:var(--shadow)}
.tool-card h1{margin:0 0 8px;font-size:clamp(27px,4vw,38px);line-height:1.15}
.lead{color:var(--muted);margin-top:0}
.form-grid{display:grid;grid-template-columns:1fr 1fr;gap:15px}
.field label{display:block;font-weight:800;font-size:14px;margin-bottom:6px}
.field input,.field select{width:100%;padding:13px;border:1px solid #d0d5dd;border-radius:10px;font-size:16px;outline:none;background:#fff}
.field input:focus,.field select:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(37,99,235,.1)}
.actions{margin-top:18px}
.result{display:none;margin-top:20px;background:#eff6ff;border:1px solid #bfdbfe;border-radius:14px;padding:18px}
.result.show{display:block}
.result strong{font-size:25px;color:var(--primary)}
.explain{background:#fff;border:1px solid var(--border);border-radius:16px;padding:23px;margin-top:22px}
.explain h2{font-size:22px;margin-top:0}
.explain h3{font-size:18px}
.explain code,.formula{background:#f1f5f9;border-radius:8px;padding:3px 7px}
.related{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin-top:15px}
.related a{padding:14px;background:#f8fafc;border:1px solid var(--border);border-radius:11px;font-weight:700;font-size:14px}
footer{margin-top:45px;background:#111827;color:#cbd5e1;padding:35px 0}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr;gap:30px}
footer h3{color:#fff;margin-top:0}
footer a{display:block;margin:7px 0;color:#cbd5e1;font-size:14px}
.small{font-size:13px;color:#94a3b8}
.notice{padding:12px 15px;background:#fff7ed;border:1px solid #fed7aa;border-radius:10px;color:#9a3412;font-size:13px}
@media(max-width:900px){.grid{grid-template-columns:repeat(2,1fr)}.footer-grid{grid-template-columns:1fr 1fr}}
@media(max-width:650px){
 .container{width:min(calc(100% - 22px),var(--max))}
 .navlinks{display:none;position:absolute;top:68px;left:0;right:0;background:#fff;border-bottom:1px solid var(--border);padding:15px 20px;flex-direction:column;align-items:flex-start}
 .navlinks.open{display:flex}.menu-btn{display:block}
 .grid{grid-template-columns:1fr}.hero{padding:38px 0 22px}.form-grid,.related,.footer-grid{grid-template-columns:1fr}
 .tool-wrap{padding:22px 0}.tool-card{padding:18px}
}

.brand-mark{display:inline-flex;align-items:center;gap:9px}
.brand-icon{width:34px;height:34px;border-radius:10px;background:linear-gradient(135deg,#7c3aed,#2563eb);color:#fff;display:grid;place-items:center;font-size:18px;box-shadow:0 5px 15px rgba(124,58,237,.25)}
.tagline{font-size:13px;color:var(--muted);font-weight:600;margin-left:3px}
.category-pill{display:inline-block;padding:5px 9px;border-radius:999px;background:#f3e8ff;color:#6b21a8;font-size:11px;font-weight:800;margin-bottom:9px}
.hero .eyebrow{display:inline-block;padding:7px 11px;border-radius:999px;background:#ede9fe;color:#6d28d9;font-weight:800;font-size:12px;margin-bottom:14px}
.tool-card .card-icon{font-size:30px}