:root { font-family: system-ui, sans-serif; line-height: 1.5; }
body { margin: 0; }
header { padding: 2rem; background: #f5f5f5; }
main { padding: 2rem; max-width: 700px; margin: 0 auto; }
button { padding: .6rem 1rem; border: 1px solid #ccc; border-radius: .5rem; background: white; cursor: pointer; }
button:hover { background: #f0f0f0; }