Main Nav looks buggy between 1.024px and 1.400px

Hi there.

The main nav looks good at screens with a width of more than 1.400px and also looks good below the 1.024px breakpoint when it change in to mobile nav. But between 1.024px und 1.400px the main nav appears buggy.

What can I do to have a consitent good looking main nav?

Many thanks

Holger