.theme-demo {
  padding: 20px;
  border-radius: 8px;
  margin: 15px 0;
  text-align: center;
}

/* Fallback for browsers without custom property support */
.theme-demo {
  background-color: #3498db;
  color: white;
}

@supports (--custom: value) {
  .theme-demo {
    --primary-color: #e74c3c;
    --text-color: white;
    background-color: var(--primary-color);
    color: var(--text-color);
  }
}