Layout Breaks in Firefox

Associated files governing layout appear to be missing when viewing my site in Firefox only (Safari & Chrome show up exactly as expected and look great). Through searching I have found a couple of possible solutions, but none have been successful for me yet. I’m hoping to go live with the site within a few days so help is greatly needed.

Thanks for your help.

Site is viewable at:
http://www.alexhudsondesign.com/JonahPlatt/