limbo - 9:53 am on Nov 13, 2012 (gmt 0)
You need to employ a CSS reset. And also validate your HTML/CSS
This will help solve some bugs - others come with experience of knowing what will and won't work for each browser. Internet Explorer in particular will make you go grey.
Lastly you should also try and test you site on Mac - fonts render truer on OSX than windows so the spacing of letters is wider. This can throw out a layout too.