trans-style.css

html,
body {
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  background: #a0a0a0;
}

.container {
  width: 320px;
  height: 180px;
}
.container .color {
  height: 30px;
}
.container .color div {
  height: 30px;
  width: 0;
}
.container .color .blue {
  background: #5BCEFA;
  animation-name: slide;
  animation-duration: 2.5s;
  animation-iteration-count: infinite;
}
.container .color .pink {
  background: #F5A9B8;
  animation-name: slide;
  animation-duration: 2.5s;
  animation-iteration-count: infinite;
  animation-delay: 0.1s;
}
.container .color .white {
  background: #ffffff;
  animation-name: slide;
  animation-duration: 2.5s;
  animation-iteration-count: infinite;
  animation-delay: 0.2s;
}
.container .color .pink2 {
  background: #F5A9B8;
  animation-name: slide;
  animation-duration: 2.5s;
  animation-iteration-count: infinite;
  animation-delay: 0.3s;
}
.container .color .blue2 {
  background: #5BCEFA;
  animation-name: slide;
  animation-duration: 2.5s;
  animation-iteration-count: infinite;
  animation-delay: 0.4s;
}


@keyframes slide {
  10% {
    width: 0;
    float: left;
  }
  37% {
    width: 100%;
    float: left;
  }
  63% {
    width: 100%;
    float: right;
  }
  90% {
    width: 0;
    float: right;
  }
}