Jquery Sortable breaks firefox's css active feature (also focus?)

Jquery Sortable breaks firefox's css active feature (also focus?)

Bug appear in Firefox browser. Not in Chrome nor IE. (Didn't test other browsers).

Once you use some jquery sortable functions:
$( "#sortable" ).sortable();
$( "#sortable" ).disableSelection();

on html elements like (i.e. td or li)
The css active (also focus?) will stop having an effect from now on (as if it's not there).

So if you have a sortable li (like in site example) and a css command:

li:active{
  background-color: green;
  cursor: n-resize;
}

and u use
$( "li" ).sortable();
The css above will stop working.

As seen in this fiddle: http://jsfiddle.net/9pqywyxm/3/

In fiddle when you try to change li position:
In Chrome background will become green as the active css specifies.
In Firefox nothing will happen to background- as the active css is ignored.
I recommend trying in chrome and Firefox to see the difference.

Thank you.