chromium/third_party/blink/web_tests/external/wpt/css/css-images/cross-fade-target-alpha-ref.html

<!DOCTYPE html>
<html>
  <head>
    <title>CSS reftest Reference</title>
    <style>
      .outer {
        display:block;
        width: 500px;
        height: 500px;
        padding: 50px;
        background: linear-gradient(90deg, red, green);
      }
      .inner {
        display: block;
        width: 100%;
        height: 100%;
        color: white;
        background: linear-gradient(#e66465, #9198e5);
        opacity: 0.6;
      }
    </style>
  </head>
  <p>The inner gradient should be (in total) 60% covering over the outer.</p>
  <div class="outer">
    <div class="inner">
    </div>
  </div>
</html>