Sorry if this has been asked before, had a quick search and found nothing!

Basically, I've dabbled in web design before but never really understood HTML+CSS fully. I want to properly learn it now so that I am able to make simple static websites without thinking about it.

Am I best off learning XHTML & CSS2 getting used to basics, then picking up HTML5 & CSS3 or should I start with HTML5/CSS3 straight away?