css3pie leaking image from round element in ie7,8
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I was trying to create a simple rotating planet with css and javascript. First I tried to put the image as a background, which worked fine in all browsers but the background-position animation had very poor performance in IE and quickly raised RAM usage (50-100 MB increase per second) until the browser crahsed. Then I decided to try using image in the planet div and animate its position which resulted in smooth animation with low memory consumption, but as you can see in the image below the image leaks beyond the border. The planet div has `border-radius: 50%`.

I've tried adding `overflow: hidden` to the planet but that didn't work. Is there a way, to prevent the leak from happening other than using some kind of mask?

![planet][1]


  [1]: http://i.stack.imgur.com/vWgZJ.png