How can make megamenu shorter ?

Hi,
I used Postnote template and try to modified this template in RTL please i want to make shorter megamenu width that you can find in attachment .
thanks in advance.

IF I'm not mistaken, on Main Menu, the primary category of those drop-section, you'll find the width that you can change, if not, use megamenu.css to change it.

Thanks for your help