title: Where is CSS for jQuery UI's .ui-selected Defined?
body: <p>I'm trying to apply jQuery UI Selectable to a portion of my website.  However, I do not see either the selection box while dragging the mouse, nor does the color of selected <code>li</code> elements change.</p>
  
  <p>So to understand the problem, I went back to the source:</p>
  
  <p><a href="http://jqueryui.com/demos/selectable/" rel="nofollow">http://jqueryui.com/demos/selectable/</a></p>
  
  <p>I see (using IE9 developer tools) that a style <code>.ui-selected</code> is applied to selected elements.  Using Trace Styles, IE shows that <code>background-color</code> is originally defined in <code>jquery-ui.css</code> but overridden (ultimately) by <code>#selectable .ui-selected</code>.  However, IE does not show the source of <code>#selectable .ui-selected</code>.  Searching the jQuery UI style sheet I reference, <code>jquery-ui-1.8.18.custom.css</code>, finds no mention of <code>ui-selected</code>, nor do I find it in <code>jquery.ui.selectable.css</code>.</p>
  
  <p>Where exactly is the demo page getting the CSS for the background color?</p>