overflow:auto;is a property of the class
floatbecause I'm lacking in knowledge on this area... :)
overflow: auto;property on the parent being the way to do this... reading through it seems that there were many idea of how to accomplish this objective, but that method was a "surprise" to the author. The explanation is somewhat short on technical detail of why it works, see if you think that it seems that way to you?
.icon-bar aelements to confirm this. You can see the first one only because it has a background set on the
.activeclass. Without changing the overflow property on the parent it has no height, so you don't get the background color you expected.