Mobile menu issue (?) in Wedding Theme

Hello again -- I'm playing with the one-page Wedding Theme (https://www.balbooa.com/showcase/select-gridbox-theme/wedding) and observed that in tablet-mobile view, when you scroll down and up (the 2nd version of the menu shows up) after clicking the menu icon, the menu will not show up in full height (it is restricted by the header) -- see pics below -- could you please provide the code to fix it - thank you!!

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