First go to qa-styles.css & seach for
@media (min-width: 980px) .qa-sidepanel
then increase the width as much you want, for example, you want to increase it by 2% then change the width value to 27%
then go to @media (min-width: 980px) .qa-main
and less the amount you added to the above class, like here we added 2% so we will less 2% from width so now width will become 72.5% and save that file. That's it you are done!