What's the total width of the box? Careful, though: this is trickier than it seems.

150px125px75px

Perfect! In order to get the total width of the box, we add the padding, borders and margins on the right and the left side to the width of the actual content.

Whoops! In order to get the total width of the box, we add the padding, borders and margins on the right and the left side to the width of the actual content.