body{
    margin:0;
    padding:0;
    height:100%;
    width:100%;
}

.container{
    height:100vh;
    width:100%;
    background-image: url(images/a.png);
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    transition: 5s;


    animation-name:animate;
    animation-direction:alternate-reverse;
    animation-duration:30s ;
    animation-fill-mode:forwards ;
    animation-iteration-count: infinite;
    animation-play-state:running ;
    animation-timing-function: ease-in-out;
}

@keyframes animate{
    0%{
        background-image: url(images/b.png);
    }
    20%{
        background-image: url(images/c.png);
    }
    40%{
        background-image: url(images/d.png);
    }
    60%{
        background-image: url(images/e.png);
    }
    80%{
        background-image: url(images/f.png);
    }
    100%{
        background-image: url(images/g.png);
    }
}