If you ARE still seeing this issue, you will need to delete the CSS theme files located in
Windows:
C:\Program Files\Inductive Automation\Ignition\data\modules\com.inductiveautomation.perspective\themes
macOS:
/usr/local/ignition/data/modules/com.inductiveautomation.perspective/themes
You would need to restart your gateway after deleting these files so that the new files can be placed properly.