I've never run into this particular browser bug before, so I though it would be good to mention it to the community here. I have a page that's been online for about a month. Someone reported to me that in IE8 one line of text was an incorrect color.
I checked my local file and it looked fine, but when I checked the page online, sure enough instead of being gold, the line was black -- nearly invisible against the background image. Clicking on the Compatibility View icon did fix it. That's small comfort, however.
The problem appears to be deep in the CSS specificity, but after 10 minutes of detective work, I just couldn't be bothered to investigate any further. I slapped a span tag around the line and forced IE8 to use the color I intended.
The HTML and CSS both validate and every other browser (including earlier versions of IE) got the display right.
So I've learned another IE lesson - always proof my work online, not just locally.