The body gets displaced (and part of the content disappears) on ie7

Question

I have been searching for a way to fix this problem for a while now.

It seems something could be wrong on the javascript, or maybe it has something to do with the positioning.

This page http://www.medspilates.cl/ works fine on FF, on Chrome, on Safari and on IE8, but on ie7 it doesnt, the body gets displaced to the right and the main content disappears, it's also happening on ie6 (it didnt but now it does).

Sorry to post the full page but i can't pin point the exact problem except maybe the function i'm using for positioning

$(document).ready(function(){var height = $(window).height();
          $('#menu').css('margin-top', $(window).height() - $(window).height() /4)
          $('#post1').css('margin-left', $(window).width() - $(window).width() /1.125)
                           })

any help would be apreciated since I just cant find the answer.