We are experiencing black background on our sparklines graphs since updating to the 2.0.1 version.
Example image attached.
Keywords: sparklines, black
Attachment: Black sparklines example.
Screen Shot 2013-12-19 at 12.49.02.png
Deleting the widget from the panel and including it again seems to have fixed this. We have red on white graphs now as expected.
Deleting - re-adding the widget should fix it for all.