It's a lost battle, benlyboy. To resize an image to match the user's selected font size will be difficult work and doesn't add that much to the usability of the page. And you have to take side effects in account too - if element sizes get stretched beyond their designated limits and if that could mess up the general layout etc. I'd say it's easier to select a favorite font size and define that with ems or percentages, so a user can resize them at will, and spare yourself the work of trying to reach the perfect, universal, identical layout. Skip the issue by using relative font sizes and focus on other areas that need work.
FWIW, here's a site that has an extensive summary how various fonts in various sizes look like on (guess what) various platforms: