Comment 9 for bug 605517

Hmm, well if I'm opening the floodgates to <Style> tags I might as well add it to the Library as well.

Using the <Style> on the library seems to break the <BgColor><FgColor><BgColorRowEven> and <FgColorRowEven> tags so you will need to do these with QSS:

Here is an example of various handy selectors to play with:

                <Style>
                  WLibrarySidebar { background: black; color: purple; } /* Specifically select the sidebar for skinning */
                  QLabel { color: pink; } /* The label on the AutoDJ page can be styled with this. It doesn't have a good name as the analyze ones do below */
                  QPushButton { background: red; } /* Style all buttons eg AutoDJ enable button and Analyze button */
                  QTableView { background: red; } /* The Browse Feature uses a QTableView, not a WTrackTableView */
                  QRadioButton { color: purple; background: red; } /* Style radio buttons such as those in the Analyze section */
                  #radioButtonRecentlyAdded { background-color: blue; } /* The specific name of the recently added radio */
                  #radioButtonAllSongs { } /* The specific name of the all songs radio button */
                  #pushButtonSelectAll { } /* The name of the select all push button in analyze */
                  #pushButtonAnalyze { } /* The name of the analyze button in the analyze view */
                  WTrackTableViewHeader { color: red; } /* This is the QHeaderView applied to all WTrackTableViews */
                  WTrackTableView { background: black; alternate-background-color: grey; } /* The WTrackTableView is the table that all mixxx tracks are in */
                  QToolTip { background-color: red; color: #0000FF; border-radius: 10px; } /* This styles all tooltips within the library */
                  WSearchLineEdit { background: pink; color: green; } /* This styles the QLineEdit that is the search box */
                </Style>

You can also style scrollbars like this:
http://doc.trolltech.com/4.5/stylesheet-examples.html#customizing-qscrollbar

Unfortunately there is no good way to style the help text on the Crate or Playlist pages.