:root {
  color-scheme: light dark;
  --ink: #172033;
  --muted: #5f6878;
  --line: #dce2eb;
  --surface: #ffffff;
  --canvas: #f5f7fb;
  --accent: #0969da;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--canvas);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
}

a { color: var(--accent); }

.shell { max-width: 760px; margin: 0 auto; padding: 24px; }

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 12px 0 40px;
}

.brand { color: inherit; font-weight: 700; text-decoration: none; }

nav { display: flex; flex-wrap: wrap; gap: 16px; }
nav a { color: var(--muted); text-decoration: none; }

main, .card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 20px;
}

main { padding: clamp(28px, 6vw, 56px); }

.eyebrow { color: var(--accent); font-size: .9rem; font-weight: 700; letter-spacing: .04em; text-transform: uppercase; }
h1 { font-size: clamp(2rem, 7vw, 3.8rem); letter-spacing: -.045em; line-height: 1.05; margin: 12px 0 20px; }
h2 { font-size: 1.25rem; margin-top: 40px; }
p, li { color: var(--muted); }
.lead { font-size: 1.18rem; max-width: 580px; }

.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 32px; }
.button { background: var(--accent); border-radius: 10px; color: white; display: inline-block; font-weight: 700; padding: 11px 16px; text-decoration: none; }
.button.secondary { background: transparent; border: 1px solid var(--line); color: var(--ink); }

.notice { background: color-mix(in srgb, var(--accent) 8%, transparent); border-radius: 12px; margin-top: 28px; padding: 16px; }
footer { color: var(--muted); font-size: .9rem; padding: 32px 0 8px; }

@media (prefers-color-scheme: dark) {
  :root { --ink: #eef2f8; --muted: #b5bdcb; --line: #313b4c; --surface: #182131; --canvas: #101722; --accent: #58a6ff; }
}

@media (max-width: 520px) {
  header { align-items: flex-start; flex-direction: column; padding-bottom: 24px; }
  main { border-radius: 16px; }
}