:root {
  --bg: #f7f7fb;
  --text: #1c1b29;
  --muted: #5f5d72;
  --card: #ffffff;
  --line: #e3e2ee;
  --link: #5b3fd6;
  --brand: linear-gradient(135deg, #6366f1, #6d28d9);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12121a;
    --text: #ececf4;
    --muted: #a5a3b8;
    --card: #1c1c27;
    --line: #2c2b3a;
    --link: #a99bff;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 17px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}
header, main, footer { max-width: 720px; margin: 0 auto; padding: 0 20px; }
header { padding-top: 24px; }
.brand {
  display: inline-flex; align-items: center; gap: 12px;
  color: var(--text); text-decoration: none; font-weight: 700; font-size: 20px;
}
.brand img { border-radius: 10px; }
h1 { font-size: 34px; line-height: 1.2; margin: 32px 0 8px; letter-spacing: -0.02em; }
h2 { font-size: 22px; margin: 36px 0 8px; }
h3 { font-size: 18px; margin: 24px 0 4px; }
a { color: var(--link); }
.muted { color: var(--muted); margin-top: 0; }
ul { padding-left: 22px; }
.callout {
  background: var(--card); border: 1px solid var(--line); border-left: 4px solid #6366f1;
  border-radius: 12px; padding: 16px 18px; margin: 24px 0;
}
.button {
  display: inline-block; background: var(--brand); color: #fff; text-decoration: none;
  font-weight: 600; padding: 12px 20px; border-radius: 12px;
}
footer {
  margin-top: 48px; padding-top: 16px; padding-bottom: 40px;
  border-top: 1px solid var(--line); color: var(--muted); font-size: 15px;
}