body{
    background-color: gray;
    text-align: center;
}

#carousel{
    width: 800px;
    height: 600px;
    position: relative;
    margin: auto;
}

#carousel img{
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0%;
    left: 0%;
    opacity: 0;
    transition: opacity 1s;
}

#carousel img.active{
    opacity: 1;
}