My Mobile Menu Size has changed

Hello,

My site is using the Upfront Spirit theme and recently the mobile menu has changed to a much smaller size than it should be.

It was last modified to fill the mobile screen, with the options aligned to the left of the page.

Currently, the menu is very small and requires users to scroll. How can this be fixed?
The background of the menu items has also changed to a dark grey. I'm not sure why.