Case 3: Two or Three of the Three Values are “Auto”

There are two possible cases: One case is where width is auto, and one where width has some other value. First, if width is auto, the width value is the one that is calculated using the formula in Figure 8.17. That is, the width will be maximized after consideration of the margin size. Any margins set to auto will become 0.

If width is not auto, but both margin-left and margin-right are, the two margins will be of equal size and as large as possible.