.checkbox {
   background-image: url(../../image/custom/checkbox/checkbox.png);
   background-position: center center;
   background-repeat: no-repeat;
   cursor: pointer;
   display: inline-block;
   height: 16px;
   width: 16px;
}
.checkbox:hover {
   background-image: url(../../image/custom/checkbox/checkbox-hover.png);
}
.checkbox.checked {
   background-image: url(../../image/custom/checkbox/checkbox-checked.png);
}
.checkbox.checked:hover {
   background-image: url(../../image/custom/checkbox/checkbox-checked-hover.png);
}