:root { color-scheme: light dark; }
* { box-sizing: border-box; }
body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  margin: 0 auto; padding: 0 16px; line-height: 1.5; max-width: 880px;
}
header { display: flex; justify-content: space-between; align-items: center; padding: 16px 0; border-bottom: 1px solid #ccc; }
nav a { text-decoration: none; }
main { padding: 16px 0; }
footer { padding: 24px 0; color: #777; font-size: 0.9em; }
form { display: grid; gap: 8px; max-width: 320px; }
label { display: grid; gap: 4px; }
input { padding: 8px; font-size: 1em; }
button { padding: 8px 16px; font-size: 1em; cursor: pointer; }
pre { background: #f4f4f4; padding: 12px; overflow:auto; }
code { background: #f4f4f4; padding: 1px 4px; }