It is difficult to guess not haven seen the page about which you wrote. Could you post the URL to the page having the problem or post the full HTML page which can be used to reproduce your problem?
You can fix the problem if you include CSS body { font-size: 75%; }
on your page. Moreover you should always write the page in one HTML or XHTML dialect which you define in the corresponding <!DOCTYPE
If you don't fix validation errors then you have much more probability that your page will look different in different web browsers or different versions of the same browser. It means that the web browser try to guess what you mean. So I try to validate my pages always in http://validator.w3.org/