Never

SO YOU... use tables for laying out your web pages, constantly make your headings from images, favour xhtml transitional, worship Internet Explorer, believe an I.D. is a common everyday identifier, and espouse that open source is a scourge on society.......
OUT OUT of the class now...........
do not return.... until you wipe the slate clean
padding: 0px 0px 0px 0px
margin: 0px 0px 0px 0px
or hide.... your face
.hideme {
visibility: hidden;
}
Our class has principles

Image: 'don9t do this'
www.flickr.com/photos/75125403@N00/2094415296