:root {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
  color: #1f2937;
  background: #f7f7fb;
}
* { box-sizing: border-box; }
body { margin: 0; }
main {
  max-width: 820px;
  margin: 0 auto;
  padding: 48px 24px 72px;
}
.card {
  background: white;
  border: 1px solid #e5e7eb;
  border-radius: 16px;
  padding: 32px;
  box-shadow: 0 8px 28px rgba(0,0,0,.05);
}
h1, h2 { line-height: 1.2; color: #111827; }
h1 { margin-top: 0; }
h2 { margin-top: 2rem; }
a { color: #3158d4; }
.small { color: #6b7280; font-size: .95rem; }
nav { margin-bottom: 24px; }
ul { padding-left: 1.25rem; }
code {
  background: #f3f4f6;
  padding: .1rem .3rem;
  border-radius: 4px;
}