What is your recommendations in the use of complex CSS? What are the performance impact? Does the browser really reload the CSS on every mouse move?
Most of my CSS selectors are pseudo classes to avoid using class names and to limit ID names. Just makes for cleaner HTML code.

haven't had any problems so far. BTW, I'n not concerned with IE compatibility or lack there of. With computers being mega fast nowdays should I be concern with a performance hit? The reason I'm asking is because alot of HTML validators including GTMetrix complain about using more than 2 selectors in CSS.

div#TopMenu li:nth-last-child(2):hover > p::after{content:url(../images/new.png);}

the above will insert an image in the paragraph element when the next to last list element is hovered in the TopMenu div

I have not yet explored advanced CSS3, don't know about the others who come in here. You could put a wee sample of the code above on a web page, just to illustrate what you mean .

But whether or not you should use it, if it validates or not, I believe comes down to your clientel; viewers to your site. What kind of browsers do they use? Do you have a lot of corporate or instituional viewers? If yes, then think about how long it takes before they are able (or even allowed) to upgrade their browsers.

If you have statistics showing what equipment your viewers have, then you ought to build your sites so that they will work, even if it's IE6.

Thanks Inger !! You have a very good point. Yes some corporations, even here in the USA are STILL using IE6 because they think its SAFE. Believe or not, my client upgraded to IE7 a few months ago. Well heck with them being so yesterday. they will see the error of their ways one day. occurring to browser usage stats on W3schools site IE8 was used 16% last month and Firefox was used 42%.

most of my visitors use firefox or safari and oddly 16% use IE8. My website is a Celebrity official fan club for the fomer Disney singer / actress Celeste Kellogg. http://www.CelesteKelloggOfficialFanClub.com Yes I know the site looks like crap in IE8 and don't care. My main concern is that it looks and performs well in modern browers and reasonably well as android, ipad, samsung cell phones.

Woops! I think I went off subject here. oh well (slap, slap) turns other cheek.
Daryl

I had a look at your site with FF4 and IE8, and the latter got a message about outdated browser . But I prefer to wait a bit before updating to IE9, until the worst bugs have been reported and fixed.

Thats probably a good move. I heard IE9 is not 100% compatialbe yet and some ppl have reported crashing issues. I have not tried IE9 personally. Agree with you wait until the bugs get fixed