Add border to objekt while draging/reorder

Add border to objekt while draging/reorder

I need to add a border while draging and reorder a table within a list:

  2. $(function () {
  3.           $("#sortable").sortable({      
  4.               start: function () {
  5.                   $(".my-table").css("border", "1 px solid #202020");
  6.               },
  7.               stop: function () {
  8.                   $(".my-table").css("border", "none");
  9.               }           
  10.           }).disableSelection();

  12.       });

This approach doesn't work. So how could this be done?