body { margin:0; font-family: Arial, sans-serif; background:#111; color:#eee; }
header { background:#000; padding:1em 0; display:flex; justify-content:center; }
header nav a { color:#fff; margin:0 1em; text-decoration:none; font-weight:bold; }
.hero { width:100%; display:block; }
section { padding:2em; text-align:center; }
button, .btn {
  padding:0.8em 1.2em; margin:0.5em; border:none; border-radius:6px;
  font-size:1em; cursor:pointer; background:#fff; color:#000; font-weight:bold;
}
footer { background:#000; color:#aaa; text-align:center; padding:1em; }