CSS gradients not displaying on old versions of IE and Firefox

.horizontalTabGradient
{
    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#edeff4', endColorstr='#ffffff'开发者_如何学Go, iOrientation=1); /* for IE */
    background: -webkit-gradient(linear, left top, left bottom, from(#edeff4), to(#ffffff)); /* for webkit browsers */
    background: -moz-linear-gradient(top,  #edeff4,  #ffffff); /* for firefox 3.6+ */   
}

We set the backgrounds this this CSS specifies to a lot of our buttons and grid headers throughout our app. We recently found through testing that when viewing the app on older versions of Firefox and IE, the background does not appear.

Is this just flat out not supported by the older versions? Or is there a way we can get it to work in both.

Thanks!

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Is this just flat out not supported by the older versions?

Yes.

Or is there a way we can get it to work in both.

Yes, but not with CSS alone, you need to use images.