Margin-left: 0; width = 880 margin-right: 0

Notes
The z-axis refers to how close an element appears to be to the viewer. The z-index attribute requires a numeric value. Higher numbers mean the element is closer to the user (or on top).

If you define the z-index for some elements and leave the z-index undefined for others, you have no guarantee exactly what will happen. If in doubt, just give every value its own z-index, and you'll know exactly what should overlap what.