body { font-family: system-ui, sans-serif; max-width: 720px; margin: 2rem auto; padding: 0 1rem; }
header { padding-bottom: 1rem; border-bottom: 1px solid #ddd; }
header a { margin-right: 0.5rem; }
main { padding-top: 1rem; }
.error { background: #fee; padding: 0.5rem; border: 1px solid #f99; }
input, button { padding: 0.4rem 0.6rem; margin: 0.2rem; }