:root {
  --brand: #2f80ff;
  --text: #1b2333;
  --muted: #5b6b8c;
  --card: rgba(255, 255, 255, 0.8);
  --bg-top: #c9e0ff;
  --bg-bottom: #f8fbff;
}

@media (prefers-color-scheme: dark) {
  :root {
    --text: #e8eefc;
    --muted: #a3b1cf;
    --card: rgba(255, 255, 255, 0.08);
    --bg-top: #16254a;
    --bg-bottom: #0b1220;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  line-height: 1.6;
  color: var(--text);
  background: linear-gradient(var(--bg-top), var(--bg-bottom) 60%) fixed;
}

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 48px 16px 64px;
}

h1 { font-size: 2.2rem; margin: 0 0 4px; }
h2 { margin-top: 2rem; font-size: 1.25rem; }
a { color: var(--brand); }
.muted { color: var(--muted); }

.card {
  background: var(--card);
  border-radius: 22px;
  padding: 24px;
  margin-top: 24px;
}

.button {
  display: inline-block;
  margin-top: 16px;
  padding: 14px 24px;
  border-radius: 18px;
  background: var(--brand);
  color: #fff;
  font-weight: 600;
  text-decoration: none;
}

footer {
  margin-top: 48px;
  font-size: 0.9rem;
  color: var(--muted);
}