Moving down the button to the middle HTML & CSS

http://stackoverflow.com/questions/36588404/moving-down-the-button-to-the-middle-html-css

by fido3993

HTML

<section class="background">
  <div class="row">
  
  <div class="centering">
   <a href="#" class="btn">
  Contact Us
  </a>
  </div>
 
  </div>
</section>

CSS

*{
  padding:0;
  margin:0;
}

.background{
  background-image: url(https://pixabay.com/static/uploads/photo/2016/01/19/15/06/city-street-1149159_960_720.jpg);
  background-size:cover;
  height:90vh;
}

.row{
  positon:relative;
  width:100%;
}

.centering{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
}

.btn {
    display: inline-block;
    padding: 10px 30px;
    font-weight: 300;
    text-decoration: none;
    border-radius: 200px;
    transition: background-color 0.8s;
    color: #fff;
    border: 1px solid #fff;
}