Hi @Willash029, sorry for the late reply. I did take a look at the site http://fourcreatives.com/hm-new/index.html in Firefox and IE and chrome , but I am not getting the same results as you are seeing, I can see the site looks the same in all the browsers. See my screenshots attached.
Chrome: http://note.io/1FZtKin
Firefox: http://note.io/1FZtpfy
IE 11: http://note.io/1FZtyQg
One other thing, when looking at the site, I noticed you have a few margins set with negative margins or padding, and IE and Firefox are notoriously bad at handling negative values in CSS, so I would strongly suggest not to use negative values combined with percentage widths on your site.
I hope this helps, if you still have issue, I would consider also minifying the CSS and HTML on your site during export, that can also help. Cheers, Dave