@keyframes fadeBgBanner {
    0% {
        opacity:1;
    }
    17% {
        opacity:1;
    }
    25% {
        opacity:0;
    }
    92% {
        opacity:0;
    }
    100% {
        opacity:1;
    }
}

.banner .img1 {
    animation-delay: 15s;
}
.banner .img2 {
    animation-delay: 10s;
}
.banner .img3 {
    animation-delay: 5s;
}
.banner .img4 {
    animation-delay: 0;
}

.banner .banner-img {
    animation-name: fadeBgBanner;
    animation-timing-function: ease-in-out;
    animation-iteration-count: infinite;
    animation-duration: 20s;
    width:100%;
    position:absolute;
    left:0;
    top:0;
    z-index:-9;
}