select id=test1 style="appearance:base-select">
  <option>option</option>
  <option>option</option>
</select>

<style>
  #test1::picker(select) {
    background-color: red;
  }
  #test1::picker(select):popover-open {
    background-color: green;
  }
</style>

<script>
const select1 = document.querySelector('select#test1');
const red = 'rgb(255, 0, 0)';
const green = 'rgb(0, 128, 0)';

promise_test(async (t) => {
  const style = document.createElement('style');
  document.head.append(style);
  t.add_cleanup(