.HorizontalSplitterBar
{
  background: url(../../App_Themes/Theme1/images/splitter_horColBg.gif);
}

.VerticalSplitterBar
{
  background: url(../../App_Themes/Theme1/images/splitter_verColBg.gif); 
}

.VerticalSplitterBarHover
{
  background: url(../../App_Themes/Theme1/images/splitter_verColBgHover.gif); 
}