Enlarge coloumn in Twenty XS

Hi, I m trying to modify the width of the three coloumn:
https://sixdegreesoffreedom.org/

For the right and the left is “sideX” but I cant find the code for the central coloumn, for example:

#middle {width: Xpx } doesnt work…

[closed as duplicate – please continue with the original topic (‘resolved’ marker removed) – https://www.ads-software.com/support/topic/theme-twentyxs-help-for-css?replies=10 ]