<body>
  <div class="container">
    <div class="Loading"></div>
  </div>
</body>
body {
  margin: 0;
  padding: 0;
  animation: pulse 5s infinite;
}

.container {
  position: relative;
  width: 50%;
  margin: 280px auto; 
  padding: 20px 40px;
  border-radius: 4px;
  box-sizing: border-box;
  background: #fff;
  box-shadow: 0 10px 20px rgba(0, 0, 0, .5);
}

.Loading {
  position: relative;
  display: inline-block;
  width: 100%;
  height: 10px;
  background: #f1f1f1;
  box-shadow: inset 0 0 5px rgba(0, 0, 0, .2);
  border-radius: 4px;
  overflow: hidden;
}

.Loading:after {
  content: '';
  position: absolute;
  left: 0;
  width: 0;
  height: 100%;
  border-radius: 4px;
  box-shadow: 0 0 5px rgba(0, 0, 0, .2);
  animation: load 5s infinite;
}

@keyframes load {
  0% {
    width: 0;
    background: #a28089;
  }
  
  25% {
    width: 40%;
    background: #a0d2eb;
  }
  
  50% {
    width: 60%;
    background: #ffa8b6;
  }
  
  75% {
    width: 75%;
    background: #d0bdf4;
  }
  
  100% {
    width: 100%;
    background: #494d5f;
  }
}

@keyframes pulse {
  0% {
    background: #a28089;
  }
  
  25% {
    background: #a0d2eb;
  }
  
  50% {
    background: #ffa8b6;
  }
  
  75% {
    background: #d0bdf4;
  }
  
  100% {
    background: #494d5f;
  }
}

External CSS

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External JavaScript

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