popup-menu-appearance-zero-font-size.html

<!DOCTYPE html>
<meta name=fuzzy content="maxDifference=0-3; totalPixels=0-100">
<script src="../../../resources/testdriver.js"></script>
<script src="../../../resources/testdriver-vendor.js"></script>
<script src="../resources/picker-common.js"></script>

<select>
  <optgroup label="Theropods">
      <option>Tyrannosaurus</option>
      <option>Velociraptor</option>
      <option>Deinonychus</option>
  </optgroup>
  <optgroup label="Sauropods">
      <option>Diplodocus</option>
      <option>Saltasaurus</option>
      <option>Apatosaurus</option>
  </optgroup>
</select>
<style>
option, optgroup {
  font-size:0;
}
</style>

<script>
  window.onload = openPickerAppearanceOnly(document.querySelector('select'));
</script>

chromium/third_party/blink/web_tests/fast/forms/select-popup/popup-menu-appearance-zero-font-size.html