:root{font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;line-height:1.5;color-scheme:light dark}*{box-sizing:border-box}body{margin:0;min-height:100vh}.shell{max-width:640px;margin:0 auto;padding:4rem 1.5rem}.shell h1{font-size:1.75rem;margin-bottom:.5rem}