body { margin:0; font-family: Arial, sans-serif; background:#0b0b0b; color:#fff; }
header { display:flex; justify-content:center; align-items:center; background:#000; padding:15px; }
header .logo { height:50px; margin-right:10px; }
header h1 { font-size:2rem; margin-right:20px; }
header nav a { color:#0f0; margin:0 10px; text-decoration:none; font-weight:bold; }
main { padding:20px; text-align:center; }
button { padding:10px 20px; background:#0f0; border:none; border-radius:5px; font-size:1rem; cursor:pointer; }