Hit Testing

Source Code

        #transparent-div{
            width:400px;
            height:400px;
            border-bottom-color:red;
            border-bottom-width:1px;
            border-style:solid;
            z-index:0;
        }

        #button{
            position:absolute;
            top:200px;
            left:50px;
            z-index:-1;
        }