What is the css / html `root` element?

Question

I have just recently started using NetBeans IDE (6.9.1) and have used it to add a stylesheet to my site-in-progress.

To my surprise, one element was automatically ad

Answer 1

From here: http://www.quirksmode.org/css/root.html

The :root pseudo-element selects the root of all blocks in the page, ie. the Initial Containing Block. In HTML this is obviously the element

Test stylesheet:

 :root {    
     background-color: #6374AB;
    padding: 50px; 
 } 

If the :root selector works the left and right column of the page are blue, and the white middle column is offset by 50 pixels.