Custom size/width of mega menu

Is there any way to set a custom width for the mega menu, which is set to 500px by default? I need the mega menu to be 750px wide.

I somehow fixed the issue with the full-size mega menu and the additional block, but honestly, I don’t like it this way.

Thank you!

I would like something like this, but in this case, the menu gets totally broken on smaller laptops.