few quick tips:
all headers by default would add some padding and this would result in text moving to top.
Another best way for you to debug such simple issues are, to install few addons.
On firefox you can very well use:
- Firebug: https://addons.mozilla.org/en-US/firefox/addon/1843
- Web-developer tool bar http://sumanthtechsavvy.blogspot.com/2006/04/mozilla-extensions-1.html