css/css-backgrounds/border-radius-clipping-with-transform-001-ref.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/">
<style>

#outer {
  border: 10px solid #000;
  border-radius: 60px;
  width: 200px;
  height: 200px;
  background: blue;
  position: absolute;
  top: 10px;
  left: 10px;
}

#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>
<div id="coverinner">
</div>
<div id="coverouter">
</div>