:root{color-scheme:light dark}body{font-family:system-ui,sans-serif;margin:0}.container{max-width:56rem;margin:4rem auto;padding:0 1rem}h1{font-size:clamp(1.8rem,2.5vw + 1rem,3rem);margin-bottom:.5rem}button{padding:.6rem 1rem;border-radius:.5rem;border:1px solid #888;cursor:pointer}