How to control width of div container containing other elements (blocks)?

Site URL: http://www.imanayoubi.com/design

Hi there, the forums so far have been a great help with common css problems. I thought after 2 days stuck on a development issue, I would bring it forward for some help. I am currently trying to achieve something like this that I designed: 
 

So basically four mark down boxes that are at equal length from the bottom so the final design looks even no matter what width.

Instead, I'm getting something like this:

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The main issue is I can't find the class to control the entire index section...