.demo {
            position: absolute;
            top: 100;
            left: 0;
            right: 0;
            bottom: 0;
            margin: auto;
            
            width: 99%;
            height: 450px;
            overflow: hidden;
            border: 1px solid #fefefe;
            box-shadow: 1px 1px 8px 2px rgba(0, 0, 0, .1);
        }