You can customize the text attributes and background colors of the navigation controls to fit your corporate look. For example, if you want to change the graphic of the Previous arrow, find previoustraversalarrow.png and change it.
1 Previous (previoustraversalarrow.pgn): Use this to customize the graphic (default is 16 x 16 pixels) for navigating to the previous document in the outline. There are 4 graphics showing the disabled, enabled, hover and selected states.
2 Next (nexttraversalarrow.png): Use this to customize the graphic (default is 16 x 16 pixels) for navigating the next document in the outline. There are 4 graphics showing the disabled, enabled, hover and selected states.