Header on mobile overflows when not signed in

See below:

To reproduce:

• Sign out of GitLab.com.
• Open an issue (such as this one) on your mobile device.
• Click the hamburger icon in the header, notice that the header content is overflowing.

mentioned in issue #14303 (closed)

Added frontend label

Reassigned to @iamphill

mentioned in commit b4f97b93

mentioned in merge request !3342 (merged)

Milestone changed to 8.6

Added regression label

Status changed to closed by merge request !3342 (merged)

mentioned in commit 5a349efc

mentioned in commit 5a20d3ab

Mentioned in commit maxraab/gitlab-ce@5a20d3ab