Hi there,
I am a UK-based web developer, specialising in Wordpress. I have also worked on various government websites in which user accessibility (and hence cross-browser compatibility) is paramount.
Exactly what needs to be done depends on the nature of your site, but most likely the issues are a combination of : 1) different degrees of CSS support between browsers, 2) different implementations of CSS specifications, and 3) differences in javascript functioning.
With a list of current issues, I can get to work on resolving them asap.
Please see my PM for further information.
Best regards,
-Sam Addison