I’ve changed the default stylesheet to do away with Reader’s semi-opaque dark background. Now the entire window is filled with the same background color, which I think looks better. I’ve also made the scrollbar more subtle and moved it to the right edge of the window.
If you already use CustomReader and want to check out the new look, go to the Advanced tab of CustomReader’s settings and click Restore Default. (But copy your old stylesheet to a text file first, in case you want to go back to it!)