Mysterious scroll-base-color style added at runtime in IE7

In IE7 - haven't checked IE6 - I havbe a legend element that shows up blue instead of white as it does in all other browsers. In IE's web developer toolbar, the color seems to be being set because of a scroll-base-color style setting. The trouble is that I've never heard of that style setting. I'm certainly not using it.

When I trace the style, it chooses the html element's css definition. I've tried overwriting it using something like this:

html, body, fields开发者_StackOverflowet, legend {scroll-base-color: #FFFFFF !important;}

...doesn't work.

What is going on?

---

scroll-base-color is a nonstandard CSS property supported only by Internet Explorer and Opera. Try

html {
    scroll-base-color: #fff;
}

To get it to normal.