add mkt-prompt element

![screen shot 2014-12-18 at 6 05 00 pm](https://cloud.githubusercontent.com/assets/674727/5499226/7038bf22-86e0-11e4-9834-51fe33050cce.png)

@mstriemer @spasovski 
ugh, it's [CSS 4](http://updates.html5rocks.com/2013/03/What-s-the-CSS-scope-pseudo-class-for).