container width mainpage not changing

Hi there,
I am trying since hours to change the ratio width between the left and right main container.
As soon as I change the styles id="jp-left" in my browser manually it works fine.
When I change the width within the css code, it has no effekt in the frontend it is still 50%/50%
I was also looking within the template setup, remembered there was a lot of customizing, but also the sidebar changes had no effect.
looking for some help.
Almost similar issue in top-c region, here I have two columns and need to have a 100% width of the left container, so no content will overflow to the right one.
many thanks and best
Dave

Hello,
you have to add this code into your css/custom.css

#jp-left { width:30%}
#jp-right {width:70%}

How to customize a theme
www.joomlaplates.com/template-customizing