Adjustable transparency for the widget
Some Samsung Android 6 devices had a bug that prevented the black background in the widget from displaying. This has been fixed in a system update from Samsung. Try checking your device for a system update and install it if it is available.
Didier Vojtisek commented
the behavior isn't homogeneous between light and dark themes.
light theme has a background and dark theme is fully transparent. Adjusting the transparency of the widget (all themes) would be the best solution :-)
A fully transparent option would be great.
A full transparent widget background would be sufficient an wonderful!
This would be very versatile. May also be tied into other theme options such as font shadows, colors, etc.
Or at least make able to hide background if it's easier and faster to implement. To dark this black hole on the screen :)