Now you will employ the table Property inspector to remove the extra space within the navigation buttons table & to insert a background color in the table.
1. In the Property inspector, click on the Clear Row Heights icon. It is the top left button within the lower half of the Property inspector.
The added space is eliminated through the table.
2. Yet in the Property inspector, click on the BgColor color box icon, after that use the eyedropper to choose the color black.