Rearrange sidebars on ascetica without ruining christmas

Hello there,
I have moved the navigation menu on the ascetica theme from the right hand side to the left hand side by changing
float: right;
to float: left;

I want to have the secondary sidebar sitting under the nav. bar (essentially a mirror image of the original layout) but it is currently sitting next to nav. bar like two old ladies at a bus stop and pushing out the main content.

Any ideas? How do I best set up the containers?

Thank you