:root{--bg:#fafafa;--card:#fff;--fg:#0a0a0a;--mut:#525252;--line:#e5e5e5;--accent:#4f46e5;--accent-fg:#fff;--err:#dc2626;color-scheme:light dark}
@media (prefers-color-scheme:dark){:root{--bg:#0a0a0a;--card:#171717;--fg:#fafafa;--mut:#a3a3a3;--line:#262626;--accent:#6366f1;--err:#f87171}}
*{box-sizing:border-box}
html,body{margin:0;height:100%}
body{display:grid;place-items:center;grid-template-columns:minmax(0,1fr);padding:16px;background:var(--bg);color:var(--fg);font:14px/1.5 Inter,system-ui,-apple-system,"Segoe UI",sans-serif}
.card{width:100%;min-width:0;max-width:440px;background:var(--card);border:1px solid var(--line);border-radius:12px;padding:32px 24px;text-align:center}
.lock{display:inline-grid;place-items:center;width:44px;height:44px;border-radius:10px;background:color-mix(in srgb,var(--accent) 12%,transparent);color:var(--accent);margin-bottom:12px}
h1{font-size:20px;font-weight:600;letter-spacing:-.01em;margin:0 0 4px}
.lead{color:var(--mut);margin:0 0 20px}
form{display:flex;flex-direction:column;gap:8px;text-align:left}
label{font-weight:500}
input{height:44px;width:100%;border:1px solid var(--line);border-radius:8px;background:transparent;color:var(--fg);padding:0 12px;font:600 20px/1 ui-monospace,"JetBrains Mono",monospace;letter-spacing:.25em;text-align:center;text-transform:uppercase}
input:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
input::placeholder{color:var(--mut);letter-spacing:.25em}
button{height:40px;margin-top:8px;border:0;border-radius:8px;background:var(--accent);color:var(--accent-fg);font:500 14px/1 inherit;cursor:pointer}
button:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.error{color:var(--err);font-size:13px;margin:0}
.boxes{display:flex;justify-content:center;width:100%}
.group{display:flex;gap:10px;min-width:0}
input.box{flex:0 1 56px;width:56px;min-width:0;height:60px;padding:0;letter-spacing:0;font-size:26px;text-align:center}
@media (max-width:420px){.card{padding:24px 16px}input.box{height:56px}}
a{color:var(--accent);font-weight:500}