Responsive Bug in Blogs MU theme

When placing the sidebar on the right, the css that is hardcoded into the header.php specific to the right sidebar messes up the responsive css in base.css causing it to only fill 65% of the screen.

This is true whether the sidebar is visible on the selected page or not because the if statement used to include the hardcoded css only checks to see if the theme is using the right sidebar. Also, since the css in the header.php file is !important, there is no way to override it.

When the theme options are updated to show the sidebar on the left, the site looks perfect on a mobile device.

I have found absolutely no way possible to overcome this. I'm using a child theme I created from Blog MU, so I modified the header.php file and using a 3rd party library was able to achieve a bit of success by replacing the if statement with:
<?php
include ( STYLESHEETPATH . '/mobile-detect.php' );
$detect = new Mobile_Detect;
if($tn_blogsmu_sidebar_position == "right" && !$detect->isMobile()) { ?>

This worked, sort of. The problem with this solution is that my network uses a caching plugin and is serving static pages to non-logged in users... So this idea was essentially a bust.

Any ideas you have that would allow the right sidebar and a working mobile site using the Blogs MU theme would be greatly appreciated!