2. In the left pane, click Background. Define the background color either by selecting values for Color 1, Color 2 and Color 3, or by selecting one of the Predefined Backgrounds. The viewport background immediately changes when you select the colors or predefined backgrounds.
You can specify any or all of Color 1, Color 2 and Color 3 for the desired effect.
3. To reset to the viewport to the default colors, click Reset.
4. Click Close to close the Viewport Settings dialog box.