Use Highlight Dimming - Dim all days where you don't have a plane highlighted
Use Grouped Highlights - [Plane1, Plane2, Plane3] (checked) vs [Plane1] [Plane2] [Plane3] (unchecked)
Opacity:
Theme:
Default
Monochrome
Terminal
Gaijin
CLEAR VISIBILITY SETTINGS (MAKE ALL PLANES VISIBLE)