CSS space before selector

Question

I was struggling to understand why this simple CSS class selector was not being picked by my HTML element.

.label-hi :before {
    color:green;
    content:          


        

Answer 1

So I realized that for this specific selectors I cannot have any space between the class name and the : This means that removing the empty space my CSS class is picked :

.label-hi:before {
    color:green;
    content: "Hi ! ";
}

In regular classes that space does not make any difference.

Sample here : http://jsfiddle.net/GtTcn/