mozilla-release/layout/reftests/css-blending/clipped-opacity-containing-unclipped-mixblendmode-ref.html

<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
<title>Blend mode containers shouldn't clip unclipped children to their own clip</title>

<style>

body {
  margin: 0;
}

.content {
  box-sizing: border-box;
  border: 10px solid black;
  width: 100px;
  height: 100px;
}

.clip {
  box-sizing: border-box;
  width: 300px;
  height: 200px;
  border: 10px solid black;
  overflow: hidden;
}

.opacity {
  opacity: 0.5;
}

.absolutelyPositioned {
  position: absolute;
  top: 20px;
  left: 250px;
}

.mixBlendMode {
  border-color: blue;
  margin-left: auto;
}

</style>

<div class="clip">
  <div class="opacity">
    <div class="absolutelyPositioned content"></div>
    <div class="mixBlendMode content"></div>
  </div>
</div>