Fixed subforum column width - non-fixed last post column width?
 

I want to have a fixed width for the subforum column, but the column for last post to fill the rest of the overall width of the page.

I found this thread, but as far as I understood it I must specify the witdh to 100% and not mix pixels and percentages.

If possible, please explain what I need to do in detail as I'm not an expert in coding.

Thanks in advance!