:root { --bg: #f6f7f9; --card: #fff; --text: #1b1f24; --muted: #59636e; --accent: #1f6feb; --bad: #cf222e; --border: #d0d7de; }
@media (prefers-color-scheme: dark) {
  :root { --bg: #0d1117; --card: #161b22; --text: #e6edf3; --muted: #9198a1; --accent: #4493f8; --bad: #f85149; --border: #30363d; }
}
* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; display: grid; place-items: center; background: var(--bg); color: var(--text);
       font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif; padding: 16px; }
.card { width: 100%; max-width: 420px; background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 28px; }
h1 { margin: 0 0 4px; font-size: 24px; }
p { margin: 0 0 16px; color: var(--muted); }
label { display: block; font-weight: 600; margin-bottom: 6px; }
input { width: 100%; padding: 12px; font: inherit; border: 1px solid var(--border); border-radius: 8px; background: var(--bg); color: var(--text); }
button { margin-top: 14px; width: 100%; padding: 12px; font: inherit; font-weight: 600; border: 0; border-radius: 8px;
         background: var(--accent); color: #fff; cursor: pointer; }
button:disabled { opacity: .6; cursor: default; }
.msg { min-height: 1.5em; margin-top: 12px; color: var(--bad); }