alt131 - 7:36 am on Sep 16, 2011 (gmt 0)
Hi EfeBuyuran and welcome to WebmasterWorld :)
I expect one reason rocknbil suggested validating is that browser error handling varies - so that variable has to be removed when trying to solve cross-browser differences.
Unfortunately I cannot reproduce the issue on the provided code. Have you double-checked using developer tools that there is nothing else affecting the font-size?