body {
    width: 100vw;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}
#box{
    position:relative;
    width:600px;
    height:200px;
    border:1px solid red;
    border:none;
    overflow:hidden;
}
#u{
    position:absolute;
    height:200px;
    left:0;
    display: flex;
}

img {
    height:200px;
    width: auto;
}