css/css-backgrounds/border-radius-clipping-with-transform-001.html

<!DOCTYPE html>
<title>CSS Test (Backgrounds): border-radius clipping on overflow:hidden with transforms</title>
<link rel="author" title="L. David Baron" href="https://dbaron.org/">
<link rel="author" title="Google" href="http://www.google.com/">
<link rel="help" href="https://bugs.chromium.org/p/chromium/issues/detail?id=1207151">
<link rel="help" href="https://drafts.csswg.org/css-backgrounds-3/#corner-clipping">
<link rel="match" href="border-radius-clipping-with-transform-001-ref.html">
<meta name="assert" content="The content should be clipped correctly, despite the interesting transforms.">
<meta name="fuzzy" content="maxDifference=0-48; totalPixels=0-6783" />
<style>

#outer {
  border: 10px solid #000;
  border-radius: 60px;
  width: 200px;
  height: 200px;
  overflow: hidden;
  transform: rotate(90deg);
  position: absolute;
  top: 10px;
  left: 10px;
}
#inner {
  width: 100%;
  height: 100%;
  background: blue;
  transform: translateZ(0);
}

#coverinner, #coverouter {
  position: absolute;
  border: 4px solid fuchsia;
  filter: grayscale(30%);
}

#coverinner {
  width: 196px;
  height: 196px;
  top: 18px;
  left: 18px;
  border-radius: 52px;
}

#coverouter {
  width: 216px;
  height: 216px;
  top: 8px;
  left: 8px;
  border-radius: 62px;
}

</style>

<div id="outer">
  <div id="inner">
  </div>
</div>
<div id="coverinner">
</div>
<div id="coverouter">
</div>