:root {
  --bg-dark:#0c0f16;
  --text-dark:#e9edf2;
  --bg-light:#ffffff;
  --text-light:#111;
  --accent:#1e90ff;
}

body[data-theme="dark"] {
  background:var(--bg-dark);
  color:var(--text-dark);
}
body[data-theme="light"] {
  background:var(--bg-light);
  color:var(--text-light);
}

.site-header {
  text-align:center;
  padding:4rem 1rem 2rem;
}

.logo { width:160px; margin-bottom:1rem; }

button {
  margin-top:1rem;
  padding:.6rem 1rem;
  background:var(--accent);
  color:#fff;
  border:none;
  border-radius:8px;
  cursor:pointer;
}

section { padding:4rem 1rem; max-width:1000px; margin:auto; }