Vertical center with 3 lines of code

index.html

<div class="content">
  <div class="vertical-center">Example content</div>
</div>

style.scss

.content {
  height: 300px; //Necessary to correct work
  -webkit-transform-style: preserve-3d;
  -moz-transform-style: preserve-3d;
  transform-style: preserve-3d;
  backgrount-color: #f4f4f4;
  
  .vertical-center {
    position: relative;
    top: 50%;
    transform: translateY(-50%);
  }
}