Module is removing the background color

When I use this module with a div with a background color, I see the background color flash for about 1/10th of a second and then the background color disappears. This is happening on a fresh install of drupal on both the Garland and Pushbutton themes.

I've got a node with the following HTML.

<div class="curve">New story here.</div>

I've got a css file with the following code in style.css:

.curve {
  width: 100px;
  -webkit-border-radius: 10px;
  -moz-border-radius: 10px;
  border-radius: 10px;
  background-color: #000;
}

And .curve is added to the css selector field on the css3pie configuration page.

I'm looking at the page with IE8.