I think it was Eric Meyer who first coined this expression (or at least he did where I read it first), and I think it’s something that describes what I sometimes feel. Whitespace blues is the feeling you experience when HTML tags aren’t written next to each other, resulting in weird effects, margins etc.
Some code with whitespace:
<div> <img src="cool-image.png" /> <ul> <li>Item one</li> <li>Item two</li> <li>Item three</li> </ul> </div>
Above code can, in some cases/web browsers, generate extra margins and space in the displayed layout. Sometimes the only solution is to re-write it like this:
<div><img src="cool-image.png" /><ul><li>Item one</li> <li>Item two</li><li>Item three</li></ul></div>
Sad but true. Personally, I dislike giving up on writing well-structured code just to get rid of strange whitespace. So is taking whitespace into consideration for web browsers really necessary? Or should whitespace only have any affect whatsoever within PRE tags?