CSS shortcuts to increase web development speed and facilitate maintainance
Most sites today are constantly changing their html and as a result most of them specially startups, decide not to clean the CSS garbage left behind resulting in perfomance and maintainance impact
With css shortcuts you can avoid to define css specific classes for common situations.
For example, if you want a div with float:left and margin-top:20px you have to define the selector in a css file and provide these attributes changes. With shortcuts you don't need to do that, you can simply add the classes to you div:
<div class="fl mt20"> My sweet div </div>
Where
fl stands for { float: left; }
mt20 stands for { margin-top:20px; }