Some years ago, in 2005, I attended a workshop about CSS. Andy clark told us about the near future and showed us an example of a completely CSS driven web page. We all thought that there was some kind of javascript there but Andy said that the secret was the CSS3 :target pseudo-class.
You can run this jsFiddle http://jsfiddle.net/jurquizu/Wtr4g/ for a live example.
The idea behind the :target pseudoclass is that the target element of an anchor can have its CSS rules. For example the anchor link "#info" is targetting the paragraph with id "info". When we click this link, the CSS selector p#info:target is triggered and all its rules are applied.
HTML
Click on the link to show the hidden paragraph: show me.
This is the hidden paragraph.
CSS
/* here's pseudoclass-target in action */ p#info { display:none; } p#info:target { display:block; border:2px solid red; background-color:yellow; width:250px; text-align:center; }