New Navigation breaks Drawer header

Summary

In the new navigation, the drawer header is hidden behind the top bar in the search interface.

Possibly linked to #409471 (closed) and #410711 (closed), but not duplicate.

Steps to reproduce

1. enable new navigation
2. visit https://gitlab.com/search?search=apcu&nav_source=navbar
3. click on Syntax options

What is the current bug behavior?

The drawer title and close button are hidden behind the top bar

What is the expected correct behavior?

Drawer title and button are visibles (not sure if they need to go lower, or on top z-index wise)

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com