:root { --bg: #f6f6f4; --card: #ffffff; --line: #e3e3df; --ink: #1a1a1a; --muted: #6b6b66; --btn: #1a1a1a; --btn-ink: #ffffff; }
@media (prefers-color-scheme: dark) {
  :root { --bg: #141413; --card: #1e1e1c; --line: #33332f; --ink: #f1f1ee; --muted: #a3a39c; --btn: #f1f1ee; --btn-ink: #141413; }
}
* { box-sizing: border-box; }
body { margin: 0; padding: 48px 20px; background: var(--bg); color: var(--ink); line-height: 1.5;
       font-family: -apple-system, "Segoe UI", Helvetica, Arial, sans-serif; }
main { max-width: 420px; margin: 0 auto; padding: 28px; background: var(--card);
       border: 1px solid var(--line); border-radius: 10px; }
h1 { font-size: 20px; margin: 0 0 12px; }
p { margin: 0 0 16px; }
p:last-child { margin-bottom: 0; }
.muted { color: var(--muted); font-size: 14px; }
button { font: inherit; font-weight: 600; background: var(--btn); color: var(--btn-ink); border: 0;
         border-radius: 8px; padding: 12px 18px; cursor: pointer; }
button:disabled { opacity: 0.6; cursor: default; }