During a client meeting this week, I was posed with some questions about XHTML / CSS design, and how that would affect their website. I explained all the great things that web standardized sites can provide and do, but when it came to trying to balance my approach with a few downsides, I couldn't think of any. This brings me to think that there is no downsides to a site written with XHTML and CSS. But I know that there is no such thing as a perfect code, so I ask, what are some of the direct downfalls of using web standards to design a site?
Obviously we know there is one problem we have no control over, but what else is there?