How to make CSS3 rounded corners hide overflow in Chrome/Opera

Question

I need round corners on a parent div to mask content from its childen. overflow: hidden works in simple situations, but breaks in webkit based browsers and Opera when the parent is positioned relatively or absolutely.

This works in Firefox and IE9:

CSS

#wrapper {
  width: 300px;
  height: 300px;
  border-radius: 100px;
  overflow: hidden;
  position: absolute;
}

#box {
  width: 300px;
  height: 300px;
  background-color: #cde;
}

HTML

<div id="wrapper">
  <div id="box"></div>
</div>

Example on JSFiddle

Thanks for the help!

UPDATE: The bug causing this issue has been since fixed in Chrome. I have not re-tested Opera or Safari however.

Answer 1

I found another solution for this problem. This looks like another bug in WebKit (or probably Chrome), but it works. All you need to do - is to add a WebKit CSS Mask to the #wrapper element. You can use a single pixel png image and even include it to the CSS to save a HTTP request.

#wrapper {
width: 300px; height: 300px;
border-radius: 100px;
overflow: hidden;
position: absolute; /* this breaks the overflow:hidden in Chrome/Opera */

/* this fixes the overflow:hidden in Chrome */
-webkit-mask-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAIAAACQd1PeAAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAAA5JREFUeNpiYGBgAAgwAAAEAAGbA+oJAAAAAElFTkSuQmCC);
}

#box {
width: 300px; height: 300px;
background-color: #cde;
}​

JSFiddle Example