max-width not working for IE 11

I think your problem is not coming from max-width but from main element...

The main element is not fully supported by IE11 (source).

2 solutions :

• Change your <main> element to a <div>. Demo : http://jsfiddle.net/z4s01yxz/2/
• Add main { display: block; } to your CSS. Demo : http://jsfiddle.net/z4s01yxz/1/