shrink width of left "global"nav?

Howdy - getting a new site spun up using this theme. With the left/global nav fully deployed on load, it's cutting content off one of the three boxes on the right side - it looks bad. You can see an example of this in your own preview site...screenshot attached.

 

Alternatively - is there a way to hide the left nav by default on load?

 

Hello,

Mailing you customized Blackwell theme with close left nav.

Thanks & Regards
Nitesh Raghuwanshi