Changing the font size of header tags.

Q. I want to put keywords in header tags such as H1 and H2 because my mail carrier told me that this would give me high rankings in the search engines. Will I be penalized if I use style sheets to keep the font down to a reasonable size?  

A. As mentioned in a previous answer (Where Do I Place Keywords?), it may not actually even be necessary for you to put keyword phrases into header tags. That said, we've definitely found that the use of headlines and subheadlines in your copy really helps people get the gist of your site very easily. Therefore, if you can work them into your content, also using H1 and H2 tags as specified by the W3C, is certainly a good idea. If it makes sense to also use keyword phrases within some of these headlines, then that's all the better! (If they don't make sense, then it's no big deal. Really!)

Adjusting the size of your headlines to fit with the overall look and feel of your site through cascading style sheets (CSS) is absolutely, positively fine. The search engines aren't out to force you to use a huge font size just because that's the H1 default size. Don't worry another second about that one.