overflow: hidden not working on slideout-open classes

When the menu is toggled on mobile the panel can be scrolled left on accident, or purposely. This causes usability issues. if the overflow is just not removable, is there a way to disable the panel altogether so that only the menu is interactive? I've tried putting overflow: hidden on just about every relevant element and there still is indeed plenty of horizontal scrolling space when the menu is open,

Thanks in advance