body{font-family:Arial,sans-serif;margin:0;line-height:1.6}
header,nav{padding:1rem;background:#0f172a;color:white}
nav a{color:white;margin-right:1rem}
main{max-width:1000px;margin:auto;padding:1rem}
section{padding:1rem;border-bottom:1px solid #ddd}
.dark{background:#111;color:#eee}
.dark section{border-color:#444}
button{padding:.5rem 1rem}