:root {
  color-scheme: light dark;
  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --primary: #2061ee;
  --background: #f8f9fc;
  --card: #ffffff;
  --text: #11181c;
  --muted: #6b7280;
  --border: #e5e7eb;
  --error: #b91c1c;
}

* { box-sizing: border-box; }
body { margin: 0; background: var(--background); color: var(--text); line-height: 1.6; }
main { width: min(760px, calc(100% - 32px)); margin: 40px auto; }
header, article, form { background: var(--card); border: 1px solid var(--border); border-radius: 16px; padding: 24px; margin-bottom: 16px; }
h1, h2 { line-height: 1.2; }
a { color: var(--primary); }
nav { display: flex; gap: 16px; flex-wrap: wrap; }
label { display: block; font-weight: 600; margin-top: 12px; }
input { width: 100%; padding: 12px; border: 1px solid var(--border); border-radius: 10px; font: inherit; }
button { margin-top: 20px; width: 100%; padding: 14px; border: 0; border-radius: 10px; background: var(--primary); color: white; font: inherit; font-weight: 700; cursor: pointer; }
button:disabled { opacity: .55; cursor: wait; }
.muted { color: var(--muted); }
.error { color: var(--error); }
.hidden { display: none; }

@media (prefers-color-scheme: dark) {
  :root { --background: #12161f; --card: #1b212d; --text: #ecedee; --muted: #9ca3af; --border: #374151; }
}