<div class="container">
  <div class="placeholder title"></div>
  <div class="placeholder content"></div>
</div>

.container{
  width: 300px;
  padding: 10px;
  background: #eee;
  
  margin: auto;
}
.placeholder{
  position: relative;
  background: #ccc;
  border-radius: 3px;
  
  overflow: hidden;
}
.placeholder::after{
  content: "";
  position: absolute;
  
  height: 100%;
  width: 100px;
  left: -100px;
  top: 0;
  
  background: linear-gradient(to right, transparent, #ffffff70, transparent);
  animation: reflect 800ms ease-out infinite;
}
.title{
  width: 80%;
  min-height: 20px;
  
  margin-bottom: 10px;
}
.content{
  width: 100%;
  min-height: 60px;
}

@keyframes reflect{
  to{
    left: calc(100% + 100px);
  }
}