Remove Firefox glow on focused textarea

I can't figure this one out. I'm trying to get rid of that blue glow when textarea is highlighted in Firefox.

Here's my CSS:

textarea
{
    margin:0;
    padding:0;
    width: 598px;
    height: 600px;
    resize: none;
    outline: none;
}

:focus {
      outline:0;
      outline:none;
}

It removes it in Safari, but I'm have no luck with Firefox.

Thanks! Matt