body{ background: rgb(107, 136, 255);
  margin: 0;
  overflow-x: hidden; }


#m1,#m2,#m3{ position: absolute;
  visibility: hidden;
  animation: walk 400ms infinite forwards linear; }
#m2{ animation-delay: 133ms; }
#m3{ animation-delay: 266ms; }

@keyframes walk{ 
   0%, 32%{ visibility: visible; }
  33%,100%{ visibility: hidden; }}
  
.container{ overflow: hidden;
  bottom: 0px;
  position: absolute; }

.sliding-background{ background: url('https://i.sstatic.net/yvBip.png') repeat-x;
  height: 240px;
  width: 5076px;
  animation: slide 20s linear infinite; }

@keyframes slide{ 0%{ transform: translate3d(0, 0, 0); }
                100%{ transform: translate3d(-1692px, 0, 0); }}

#mcont{ position: absolute;
  left: 50%;
  bottom: 130px;
  transform: translate(-50%, 0); }

#clouds{ position: absolute;
  left: 2000px;
  top: 30px;
  animation: 15s cloud infinite forwards linear; }

@keyframes cloud{ 100%{ left:-500px; }}

<div class="container">
  <div class="sliding-background"></div>
</div>
<div class="container">
  <div class="sliding-background"></div>
</div>

<div id='mcont'>
  <img id='m1' src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADUAAABnCAMAAACXfvq+AAAADFBMVEUAAACsfAD4OAD/pECmOaYSAAAAAXRSTlMAQObYZgAAAKFJREFUeNrt1oEGAkAQhOHu9v3fOfod25wWYEb1g63mixR6/Pvl9ntRal9VlV3NJFxJdrVO9YqDGHjVPe7vQBFKx5pLtaUq7ijV9hpji5phiKL5V+FVkH26x3YFWSfuCbiVQrfqs17/FtyKAUqrlldRoCJRUo6ifCVW/635lRau+IBGtVqfCEegkifTFA+VuJVsAlXyS9yximNWZFGUqL65J9LbE8OFiaC8AAAAAElFTkSuQmCC">
  <img id='m2' src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADUAAABnCAMAAACXfvq+AAAADFBMVEUAAACsfAD4OAD/pECmOaYSAAAAAXRSTlMAQObYZgAAAKlJREFUeNrt1IEGAkEURuGaef93bnTF6S4XqP9QBwz9X0zavf37UOs9lVqX9t55NRK36sXV/dV+VgdeLauuY35D5VEY91IKy65wtijsexDfVjOMqxnyN08pNr9CU4r3OuO6XcE6SxRJg3510qpKqvCsadVGBnXIoM5HEgXY1UmhAElsinahqAKEqkgyCnWCVGomWUVIolL8xwK6FMc2RcKxUSGJYkn1Kz0A09YSSfwAvvQAAAAASUVORK5CYII=">
  <img id='m3' src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADUAAABnCAMAAACXfvq+AAAADFBMVEUAAACsfAD4OAD/pECmOaYSAAAAAXRSTlMAQObYZgAAALdJREFUeNrU1oEGw0AQhOEk8/7v3NMV/uwxgMzmxynuK0OdHh/tejZKXVuS8sqS2aoXV+ed/tUHTsuq/TK/ocoqc5lFVJFdYeYshfs9kojyMKto/a8ipczGoxdWFyrLx1NSVp1oh7pLKZIG6wwqEjNtsuK0dcYVSVMkrylPJPVFaeX/sKWUnn1dre1RRdIrElErr04UUKgujFV8Nqcp83JOU20RJudVg4ftfUX4G5r4qK4h4MiRCwDmpxaTaztkVwAAAABJRU5ErkJggg=="></div>
  <img id='clouds' src='data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAYCAMAAACsjQ8GAAAADFBMVEUAAAD8/PwAAAAAcOzIsoEVAAAAAXRSTlMAQObYZgAAAHlJREFUeNqNkkEOxCAMxDrO//+8oBRGiDRaX+ZgX1rynAA8DWjAt0bqCqQV0AdCNEFkU/uIVVB7JXcAbOUCexkHCPsCtIPS+4eAPmE2avkj6AvejwiZOL2LsC+LgfY4YwUpBzlanG+Rwl5wXQPbvdowHTnTbW2A+/R/QA4CgdKC7TAAAAAASUVORK5CYII='>