.custom-checkbox{
  width: 20px;
    vertical-align: middle;
  height: 20px;
  display: inline-block;
  position: relative;
  z-index: 1;
  margin-right:3px;
  background: url("/Content/images/checkbox.png") no-repeat;
  background-size:contain;
 }
 .custom-checkbox:hover{
  background: url("/Content/images/checkbox-hover.png") no-repeat;
   background-size:contain;
 }
 .custom-checkbox.selected{
  background: url("/Content/images/checkbox-selected.png") no-repeat;
   background-size:contain;
 }
 .custom-checkbox input[type="checkbox"]{
  margin: 0;
  position: absolute;
  z-index: 2;            
  cursor: pointer;
  outline: none;
  opacity: 0;
  /* CSS hacks for older browsers */
  _noFocusLine: expression(this.hideFocus=true); 
  -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=0)";
  filter: alpha(opacity=0);
  -khtml-opacity: 0;
  -moz-opacity: 0;
 }