:root{--bg:#f1f5f9;--card:#fff;--ink:#0f172a;--mute:#64748b;--line:#cbd5e1;--acc:#2563eb}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){--bg:#0b1120;--card:#111827;--ink:#e5e7eb;--mute:#94a3b8;--line:#334155}}
:root[data-theme="dark"]{--bg:#0b1120;--card:#111827;--ink:#e5e7eb;--mute:#94a3b8;--line:#334155}
body{margin:0;min-height:100vh;display:grid;place-items:center;background:var(--bg);color:var(--ink);font:15px system-ui,-apple-system,Segoe UI,Roboto,sans-serif}
.box{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:28px;width:min(340px,calc(100vw - 32px));box-sizing:border-box}
h1{margin:0;font-size:22px}.sub{color:var(--mute);margin:4px 0 18px}
label{display:block;font-size:13px;color:var(--mute);margin-bottom:12px}
input{display:block;width:100%;box-sizing:border-box;margin-top:4px;padding:9px 10px;border:1px solid var(--line);border-radius:8px;background:transparent;color:var(--ink);font-size:15px}
button{width:100%;padding:10px;border:0;border-radius:8px;background:var(--acc);color:#fff;font-size:15px;cursor:pointer}
.err{color:#dc2626;font-size:13px}

:root[data-theme="dark"]{color-scheme:dark}:root[data-theme="light"]{color-scheme:light}