Codebase Browser
chromium
Go to App

chromium/third_party/blink/web_tests/fast/multicol/span/outline.html 

<!DOCTYPE html>
<p>Test an outlined element inside a spanner. Passes if there is a complete blue rectangle below.</p>
<div style="width:300px; -webkit-columns:3; -webkit-column-gap:20px;">
  <div style="position: relative">
    <div style="-webkit-column-span:all">
      <div style=" outline: 2px solid blue; height: 100px"></div>
    </div>
  </div>
</div>