Issue board scrolls with system messages

Summary

When you set a Broadcast message, a System header message or a System footer message, horizontal scrolling on the Issue board view is hidden or need to be vertically scrolled.

Environment

Version : GitLab Core 11.9
System : Debian 9

Steps to reproduce

On GitLab Core :

  • In admin settings, enable Broadcast message, System header message or System footer message
  • Create a Issue board with many columns

What is the current bug behavior?

  • User can't see horizontal scroll with System footer message :

with

  • User needs to vertically scroll before seeing the horizontal scroll with a Broadcast message or a System header message :

header

What is the expected correct behavior?

Horizontal scroll should be visible (current behavior when there are no system messages) :

without