.header-box {
  background: #e3f2fd;
  border: 1px solid #ccc;
  border-radius: 8px;
  padding: 0.5em;
  color: #000;
}

@media (prefers-color-scheme: dark) {
  .header-box  {
    background: #2b2f3a;
    border: 1px solid #444;
    color: #e0e0e0;
  }
}