Handling both Firefox 2 and 3 in your CSS files sometimes turns into a tough job.

This nifty little hack does the job:

/* Firefox 2 stuff */
.foo {
  background-color: #fff;
}
/* Firefox 3 stuff */
html>/**/body .foo {
  background-color: #000;
}

And guess what? This block of CSS validates fine on W3.

Found on: http://snipplr.com/view/7043/firefox-3-css-hack/

First of all, this could be really a useful link for web developers: MSDN page about IE 7 compatibility. I quickly read the above article and then re-read MSDN page about IE 6 compatibility and felt like I need to comment on some points:

This could be very strange but it's tested: When styling Arabic text, setting the text-transform to "capitalize" using the selector "first-letter" will break the first letter and draw it separated from the rest of the word which doesn't happen to the same text using text-transform without the selector. Try it if you're interested and let me know what you think. I personally believe it's a wrong application of the capital letters in Arabic, where the separate letter is considered a capital one, I recall the early days of Office applications doing this.