:root{
  --primary:#315efb;--primary-soft:#eef3ff;--text:#171b24;--muted:#5f6878;
  --border:#e4e8ef;--bg:#fff;--surface:#f8fafc;--max:1120px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;color:var(--text);background:var(--bg);line-height:1.65}
a{color:var(--text);text-decoration:none}a:hover{color:var(--primary)}
.container{max-width:var(--max);margin:0 auto;padding:0 20px}
.site-header{border-bottom:1px solid var(--border);background:#fff}
.nav{min-height:68px;display:flex;align-items:center;justify-content:space-between;gap:20px}
.brand{font-weight:800;font-size:22px;letter-spacing:-.03em}
.nav-links{display:flex;gap:22px;flex-wrap:wrap;font-size:14px}
.hero{padding:64px 0 48px;background:linear-gradient(180deg,#f8faff 0%,#fff 100%)}
.hero-grid{display:grid;grid-template-columns:1.15fr .85fr;gap:48px;align-items:center}
.eyebrow{display:inline-block;padding:5px 10px;border-radius:999px;background:var(--primary-soft);color:var(--primary);font-size:12px;font-weight:700;margin-bottom:14px}
h1{font-size:clamp(36px,5vw,58px);line-height:1.08;letter-spacing:-.045em;margin:0 0 18px}
h2{font-size:30px;line-height:1.2;letter-spacing:-.025em;margin:0 0 14px}
h3{font-size:19px;margin:0 0 8px}
.lead{font-size:18px;color:var(--muted);max-width:680px}
.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-top:26px}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:11px 17px;border-radius:10px;font-weight:700;font-size:14px;border:1px solid var(--border);background:#fff}
.btn-primary{background:var(--primary);color:#fff;border-color:var(--primary)}
.btn-primary:hover{color:#fff;opacity:.92}
.illustration{background:#fff;border:1px solid var(--border);border-radius:24px;padding:26px;box-shadow:0 14px 40px rgba(24,40,80,.08)}
.illus-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:20px}
.dot-row{display:flex;gap:6px}.dot{width:8px;height:8px;border-radius:50%;background:#d7ddea}
.illus-screen{border:1px solid var(--border);border-radius:16px;padding:18px;background:var(--surface)}
.illus-display{font-size:34px;font-weight:800;text-align:right;padding:14px;border-radius:12px;background:#fff;border:1px solid var(--border);margin-bottom:14px}
.key-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:9px}
.key{height:44px;border-radius:10px;background:#fff;border:1px solid var(--border);display:grid;place-items:center;font-weight:700;color:#4b5567}
.key.primary{background:var(--primary);border-color:var(--primary);color:#fff}
.section{padding:54px 0}.section-alt{background:var(--surface)}
.section-head{display:flex;align-items:end;justify-content:space-between;gap:20px;margin-bottom:22px}
.section-head p{margin:0;color:var(--muted)}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.card{border:1px solid var(--border);border-radius:16px;padding:20px;background:#fff}
.card p{color:var(--muted);margin:7px 0 15px}.card-link{font-weight:700;font-size:14px}
.tool-icon{width:38px;height:38px;border-radius:11px;background:var(--primary-soft);color:var(--primary);display:grid;place-items:center;font-weight:800;margin-bottom:15px}
.note{padding:16px 18px;border-left:4px solid var(--primary);background:var(--primary-soft);border-radius:8px;color:#35405a}
.prose{max-width:820px}.prose p,.prose li{color:#4e5868}.prose h2{margin-top:38px}.prose h3{margin-top:28px}
.formula{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;background:#f4f6f9;border:1px solid var(--border);border-radius:10px;padding:14px;overflow:auto}
.tool-box{max-width:760px;margin:28px auto 0;border:1px solid var(--border);border-radius:18px;padding:24px;background:#fff}
.form-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:14px}
label{display:block;font-size:14px;font-weight:700;margin-bottom:6px}
input,textarea,select{width:100%;padding:11px 12px;border:1px solid #ccd3df;border-radius:9px;font:inherit;background:#fff}
textarea{min-height:180px;resize:vertical}
button{cursor:pointer;font:inherit}
.result{margin-top:18px;padding:16px;border-radius:10px;background:var(--surface);border:1px solid var(--border);font-weight:700}
.footer{border-top:1px solid var(--border);padding:30px 0;color:var(--muted);font-size:14px}
.footer-links{display:flex;gap:16px;flex-wrap:wrap;margin-bottom:10px}
@media(max-width:800px){.hero-grid{grid-template-columns:1fr}.grid{grid-template-columns:repeat(2,1fr)}.nav{align-items:flex-start;padding:16px 0;flex-direction:column}}
@media(max-width:560px){.grid,.form-grid{grid-template-columns:1fr}.hero{padding-top:42px}.section{padding:42px 0}}