When you place a chart on your slide that contains a Z-axis, you will notice that unlike conventional 2D charts, these charts have distinct walls and a floor. Also by default, these walls and floor show no fill or even a border (see chart in Figure 1) — the lines you see within the walls are gridlines, and not borders. If your slide background is a solid color like white or black, these defaults could work best for you — however you may want to play a bit with changing the fill or line attributes for the wall and floor elements. Do remember though that you should leave these elements in their default state unless you have a compelling reason to change them!
Learn how to format the walls and floor of a 3D chart in PowerPoint 2011 for Mac.

