wave skeleton

wave-skeleton.md

html

    <div class="skeleton-loader"></div>

CSS

.skeleton-loader {
  width: 300px;
  height: 20px;
  background: linear-gradient(90deg, #eeeeee 25%, #dedede 50%, #eeeeee 75%);
  background-size: 200% 100%;
  animation: loading 2s infinite ease-in-out;  
} 

@keyframes loading {
  0% {
    background-position: 200% 0;
  }
  100% {
    background-position: -200% 0;
  }
}