:root { color-scheme: light; font-family: system-ui, sans-serif; color: #16344a; background: #fff; }
body { margin: 0; }
main { padding: 24px 20px; max-width: 460px; margin: auto; }
h1 { font-size: 26px; line-height: 1.3; }
p { font-size: 19px; line-height: 1.55; }
#challenge { margin: 24px 0; min-height: 65px; }
button { font: inherit; font-size: 19px; min-height: 56px; width: 100%; border: 0; border-radius: 12px; color: #fff; background: #237dba; padding: 14px; }
[hidden] { display: none; }