<!DOCTYPE html>
<link rel="help" href="https://crbug.com/1356699">
<audio>
  <div>
    <div id=test1></div>
  </div>
</audio>
<script>
getComputedStyle(test1).getPropertyValue('--a');
CSS.registerProperty({name: '--a', syntax: '<length>', initialValue: '2px', inherits: false});
test1.style.setProperty('--a', 'initial');
getComputedStyle(test1).getPropertyValue('--a');
</script>
