mozilla-release/layout/reftests/forms/button/width-erode-all-focuspadding-rtl.html

<!DOCTYPE HTML>
<html dir=rtl>
<style>

button {
  -moz-appearance: none;
  background: yellow;
  border: 2px solid fuchsia;
  padding: 2px;
  font-size: 10px;
  width: 62px;
  border-radius: 0; /* override mobile/android/themes/core/content.css */
}

span {
  display: inline-block; vertical-align: middle;
  height: 20px; width: 50px; border: 2px solid blue;
}

</style>

<button><span></span></button>