Learning about CSS
I wrote this post a while back. The content can still be relevant but the information I've linked to may not be available.
I was doing some Dreamweaver tuition the other day and my student asked if I could recommend some simple online tutorials or learning resources for CSS. I suggested a few sites but The Web Standards Curriculum from the Opera Developer website also came to mind because I have been reading  through the CSS section recently. The Web Standards Curriculum covers a range of topics but the CSS section (starting here) gives a good grounding into CSS with some useful and clearly written articles.
If you want to refresh your style sheet knowledge or if you are new to this CSS stuff, the CSS section in The Web Standards Curriculum is a good place to start.