Irregularities on mobile navigation menu

Site URL: https://therare.la

password: rarity

When I look at the mobile navigation on different devices and even switching between fullscreen and regular preview like in the video below, elements get moved around and some are unreadable. Even when they are all present, some of the boxes have different padding and such. How do I make this more uniform so that the design is clean and fits to screen regardless of the device, browser, emulator, or screen dimensions?

Thank you!