#image-canvas {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 640px;
    height: 480px;
}

#thumbnail-canvas {
    position: absolute;
    top: 50%;
    left: 15%;
    transform: translate(-50%, -50%);
    width: 80px;
    height: 60px;
}