Remove background to "Dark" theme?

[Sleepy]

Looking for how to remove the 20% opacity black background to the chat, shown here - http://i.imgur.com/82Q7z0y.png

Chat w/ partial black background on right, rest of the scene on left.

[night]

You would need to add custom CSS to remove the background yourself.

#chat_box.dark {
    background: none !important;
}