:root { --bg: #f4f6f9; --card: #ffffff; --fg: #17202c; --muted: #5d6878; --accent: #2f6fdb; --border: #d9dee6; }
@media (prefers-color-scheme: dark) {
  :root { --bg: #111418; --card: #1a1f26; --fg: #e6ebf2; --muted: #8a94a6; --accent: #4c9aff; --border: #2a313b; }
}
* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; display: grid; place-items: center; padding: 16px; background: var(--bg);
  color: var(--fg); font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; }
.card { width: 100%; max-width: 420px; background: var(--card); border: 1px solid var(--border); border-radius: 14px; padding: 24px; }
h1 { margin: 0 0 12px; font-size: 1.4rem; }
p { color: var(--muted); }
code { background: var(--bg); padding: 1px 6px; border-radius: 6px; color: var(--fg); }
label { display: block; margin: 16px 0 6px; font-size: .9rem; color: var(--muted); }
input { width: 100%; padding: 10px 12px; border-radius: 10px; border: 1px solid var(--border); background: var(--bg); color: var(--fg); font: inherit; }
button { margin-top: 16px; width: 100%; padding: 12px; border: 0; border-radius: 10px; background: var(--accent); color: #fff; font: inherit; font-weight: 600; cursor: pointer; }
button:disabled { opacity: .6; }
#msg { min-height: 1.5em; }