#blocker {

                position: absolute;

                width: 100%;
                height: 100%;

                background-color: rgba(0,0,0,0.5);

            }

var blocker = document.getElementById( 'blocker' );
blocker.style.display = 'none';
blocker.style.display = '-webkit-box';
                        blocker.style.display = '-moz-box';
                        blocker.style.display = 'box';