.frame {    
    position: absolute;
    height: 200px;
    width: 400px;
    background-color: silver;
}

.panel {
    position: absolute;
    top: 0;
    bottom: 0;
    right: 0;
    left: 0;
    
    background-color: orange;
    text-align: center;
    overflow-y: auto;

    transition: left 0.4s ease, right 0.4s ease;
}

.panel:hover {  /* media query equivalent */
    left: 100px;
    right: 50px;
}