Question: According to this quirksmode article, <http://www.quirksmode.org/css/display.html> 

> 
> A block has some whitespace above and below it and tolerates no HTML
>  elements next to it, except when ordered
> 
> 
> 

Are the whitespace above or below stated in pixels or is it just 'whitespace'?.

Answer: 
In the given context, "whitespace" is a gross misnomer. Whitespace in terms of text should *never* directly interfere with the layout of non-inline block boxes; what you should see between block boxes are *margins* (usually of said boxes), which are completely different.

Margins are indeed stated in pixels. In fact, they may be stated with any CSS length unit; see the [`margin` properties](http://www.w3.org/TR/CSS21/box.html#margin-properties) in the spec. You don't specify a pixel length for whitespace directly for elements that flow inline; that is usually controlled by `font-size` instead, but when working with block boxes that should be entirely irrelevant.
You can use the padding or margin properties of a CSS element to specify such a thing (in any CSS unit, including pixels). You many specify something like:

```
.class 
{
   padding-left: 4px;
   padding-top: 3px;
}

```

The difference between padding and margin has to do with display. The padding property puts some 'whitespace' (rather clear space, whatever is behind the element will show there) between the element and its neighbor. A margin increases the size of your element around its content; the extra space will show up as whatever background the current element has.