Spring Into HTML and CSS

Containing Blocks

Another important concept when working with CSS positioning is the containing block. A containing block is any parent block box to the element you're trying to position. Consider Example 12-2.

Example 12-2. Understanding containing blocks

<div id="content"><h1>The Black Cat</h1><h2>By Edgar Allen Poe</h2><p>I married early, and was <a href="http://www.poemuseum.org/">happy to find</a> in my wife a disposition not uncongenial with my own. Observing my partiality for domestic pets, she lost no opportunity of procuring those of the most agreeable kind. We had birds, gold fish, a fine dog, rabbits, a small monkey, and a cat.</p><p>This latter was a <a href="http://www.poemuseum.org/">remarkably</a> large and beautiful animal, entirely black, and sagacious to an astonishing degree. In  ...