How do I override the plugin's CSS?

I am having some trouble styling elements in the Status widget. On my page, I would like to hide the links to Video and Image with a simple "display: none". The following code works in Firebug, but not when I add it to my child theme's style.css file, no mater how specific I make it.

#wdqs-video-switch {display: none;}

I'd also like to align the Draft button to the left, change the font color on the Post button, and do a few other things, but none of my attempts to override the CSS of this widget have worked.