html { font-family: system-ui, sans-serif; background: #f7f7f7; }
body { margin: 0; }
main { max-width: 720px; margin: 12vh auto; padding: 32px; background: white;
       border-radius: 12px; box-shadow: 0 2px 12px #0001; }
h1 { margin-top: 0; }