Welcome the the world of different browsers and the issues they have.
Even within one browser different versions have different problems depending on what tags you are using.
All I can say is to grab your header html stick in in your editor and test it with different browsers.
Some html editors even have a test mode with suggestions for different browsers to correct errors.
Or you might end up with multiple headers that read the browser and display the correct one.
But I don't think you will ever get one to work on all the browsers out there.
I would target on the most common ones used at your site.
Also a link to your page may help some to be able to make suggestions.
Last edited by Ruben; 02/26/2012 3:06 PM. Reason: Added Comment