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chromium/third_party/blink/web_tests/external/wpt/html/select/select-capitalize-sizing-ref.html 

<!doctype html>
<meta charset=utf-8>
<style>
.appearance-none {
  appearance: none;
  padding: 0;
  border: 1px solid;
}
</style>
<select>
  <option>X X X X X</option>
</select>
<br><br>
<select class=appearance-none>
  <option>X X X X X</option>
</select>