See attached
I have used a bright blue to emphasize that when I change the canvas background to a color, it does not change the top or left side of canvas background. This creates color conflict. The light blue toolbar also creates conflict and would be nice to change that color or hide completely.
Just noticed it doesn't change color on right or bottom either... so the whole background outer border remains Spotfire default blue color. Changing the background color between in Canvas styling only changes the spaces between visualizations.