top and bottom bar background is blue, should be white ( channel manager, visual editor, create content )

The following bug occurs on the HEAD ( #b1d47acbb58) of the release/14.3 branch (and not on release/saas)

Reproduction

• Select a channel in the channel manager perspective
• create content

Current situation

The background of the top and bottom bar are blue.

Desired situation

The background is white.