.demo-block {
    background: url(../images/pic11.jpg);
    background-size: cover;
    position: relative;
}

.clouds {
    position: absolute;
    top: 0px;
    left: 0;
    width: 100%;
    height: 100%;
    background: url(../images/clouds.png);
    animation: move-bg 20s linear infinite;
}

@keyframes move-bg {
    0% {
        background-position: 0;
    }
    100% {
        background-position: 2313px /* width of the image */;
    }
}

.demo-block-title-fs {
    font-weight: bold !important;
}