:root { --bg:#eef3f0; --ink:#163; }
* { box-sizing: border-box; }
body { margin: 0; font: 18px/1.5 Georgia, serif; background: var(--bg); color: #122; }
header, footer { padding: 1rem 1.2rem; display: flex; justify-content: space-between; flex-wrap: wrap; }
nav { display: flex; gap: 1rem; }
a { color: var(--ink); }
.brand { font-weight: 800; text-decoration: none; color: inherit; }
main { max-width: 640px; margin: 0 auto; padding: 2rem 1.2rem 4rem; }
label { display: block; margin: .5rem 0; }
input[type=number] { width: 5rem; }
.out { background: #fff; padding: 1rem; border: 1px solid #cdd; }
button { padding: .4rem .8rem; }