Making Content Feed Width Adjust Automatically

Hi,

We just implemented fourteen-extended plugin on our website. I’m trying to tweak our website which has 3 columns(left sidebar,content and right sidebar) in the following manner.

1) The left sidebar and right sidebar width should be constant.
2) The center content column width should adjust itself according to user’s screen resolution.
3) In high resolution displays, there is a white space column to the right since the overall width of the website does not vary according to screen size/resolution.

https://wmpoweruser.com/

https://www.ads-software.com/plugins/fourteen-extended/