Codebase Browser
chromium
Go to App

chromium/third_party/blink/web_tests/external/wpt/css/css-pseudo/slider/slider-fill-002-notref.html 

<!doctype html>
<title>::slider-fill reference</title>
<style>
  meter { appearance: none }
  ::slider-fill {
    background: blue;
  }
</style>
<meter value="0.5">