body { margin: 0; font-family: sans-serif; background: #f4f7fb; color: #1d2330; }
header { background: #0b3d91; color: #fff; padding: 14px 20px; font-size: 18px; }
main { max-width: 560px; margin: 32px auto; padding: 0 16px; }
section { background: #fff; border: 1px solid #d5deeb; border-radius: 8px; padding: 20px; }
input { display: block; width: 100%; box-sizing: border-box; margin: 8px 0; padding: 10px; border: 1px solid #d5deeb; border-radius: 4px; }
button { background: #1e88e5; color: #fff; border: 0; padding: 10px 16px; border-radius: 4px; cursor: pointer; }
#err { color: #c62828; }
code { background: #eef3fa; padding: 2px 4px; }
li { margin: 6px 0; }