As long as fade in is deactivated, .bricks-mobile-menu-wrapper is causing horizontal overflow.
My guess is it’s due to the translateX(100%) set to hide the menu (*).
Workaround:
Once you activate the fade in option, it doesn’t cause an overflow anymore.
I can share the URL privately if you want to check some details.
I am not assuming issues here but I haven’t checked in detail, if AutomaticCSS has some part in this.
( * on a side note: I am not even sure why it gets pushed out if I don’t select an option for it to that. As an user, I am not expecting that behavior.)