Control Block Formatting Context ![[Registration never required for free content]](/images/free.gif)
By: Zoe Gillenwater on Thursday, July 6, 2006
Reader Level: 
In order to become a skilled CSS developer, you need to understand the underlying concepts of CSS that make it work and not just how to produce certain visual effects. The "block formatting context" is one of those concepts that drives how CSS affects your page without you even knowing it.
Most of the time, you don't need to worry about it; it's just something that's going on behind the scenes that you don't need to get involved with. Sometimes, however, the lack of a new context can make elements interact in undesirable ways. The primary reason for setting a new context is to keep cleared elements inside a main content div from clearing floated sidebars. We'll use this problem as a case study for how to establish new block formatting contexts and to see what their effect is on the other elements around them.
