Then I come to find out that IE9 ate my PIE. PIE simply didn't work for the background gradients or rounded corners in IE9. So I pushed all the behavior declarations into an
IE lt 9 conditional comment. I also added another stylesheet for IE9. From here, I proceeded to add the necessary
DXImageTransform.Microsoft.gradient references for IE9, which doesn't support the
background: linear-gradient(...) css directive. You can see the results to the left, the DX transformation clobbers the rounded corners.
With IE9, you can do an inset box-shadow to accomplish a similar effect, without failing to work with the borders. The effect is better on buttons, and supported almost everywhere, including Opera 10.5+ ... for IE6-8 you can fall back to the linear-gradient with PIE. Also, the latest CSS3PIE disables itself for IE9, until that feature set can be flushed out.
With IE9, you can do an inline SVG background in the CSS, Microsoft even created an SVG Gradient Background Maker. It is worth noting that all the browsers (that I know of) which support CSS3 background gradients also support an SVG in the CSS directly. If you use the generation tool, you should wrap the url text in a single-quote. In other words
url(...) as the tool generates. Many CSS minifiers will have issues if the url text isn't quoted.