CSS or HTML best to optimize your web site

[clink]

Doesn't the code's semantics affect SEO? For instance if your key terms <h1> etc are nearer the top of the code is this better? Also I thought part of the reason for external style sheets (besides the obvious benefits) was to bring up the rest of the content with your keywords closer to the top of your code.

[tomfrederick]

If you want to choose between HTML and CSS then you should go for CSS, it works well. But HTML with CSS design layout performs better.