Submenu & panel width do not work on my website

Hi,
I try “Panel Width” functionality for submenus, but even with lot of tries of differents containers, I Can’t get my 100% website width on submenus.

I don’t think I’ve done something wrong, I have followed what is written here https://www.maxmegamenu.com/documentation/faqs/adjust-sub-menu-width

Any idea about the problem ? Thanks.

https://ww.wp.xz.cn/plugins/megamenu/