Adding Extra Content Boxes

The template I was using for the content slider originally had 5 boxes, but I needed 6. At first, I was confused on how to add another box, but I found out how to do it in the CSS.

The mask's width is how long the site is. When I added another content div, I had to change 500% to 600%, as there were not 6 boxes. That part was simple enough, but the width also had to change otherwise the box would be pushed down below the rest of the site. The width percentage has to be 100 divided by the number of boxes, which in my case was 16.6.