:root{--fg:#111827;--muted:#6b7280;--border:#e5e7eb;--bg:#fff}
*{box-sizing:border-box}html,body{margin:0;padding:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,Inter,Arial,sans-serif;color:var(--fg);background:var(--bg)}
.container{max-width:960px;margin:0 auto;padding:0 16px}
.nav{position:sticky;top:0;background:#ffffffcc;backdrop-filter:blur(8px);border-bottom:1px solid var(--border);z-index:10}
.nav .container{display:flex;align-items:center;justify-content:space-between;padding:12px 0}
.nav a{margin-left:16px;color:var(--fg);text-decoration:none}
.brand{font-weight:700}
.card{background:#fff;border:1px solid var(--border);border-radius:12px;padding:16px;margin:20px 0}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}
.btn{background:#111827;color:#fff;border:1px solid #111827;border-radius:999px;padding:10px 16px;cursor:pointer}
.muted{color:var(--muted)}
.result{margin-top:12px;font-weight:600}
.footer{border-top:1px solid var(--border);padding:16px 0;margin-top:24px}
@media(max-width:800px){.grid{grid-template-columns:1fr}}