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

.button{
  display: block;
  width: 400px;
  height: 40px;
  line-height: 40px;
  font-size: 18px;
  font-family: sans-serif;
  text-decoration: none;
  color: #0274be;
  border: 2px solid #0274be;
  letter-spacing: 2px;
  text-align: center;
  position: relative;
  transition: all .35s;
  border-radius: 4px;
  vertical-align: middle;
}


.button span{
  position: relative;
  z-index: 2;
}

.button:after{
  position: absolute;
  content: "";
  top: 0;
  left: 0;
  width: 0;
  height: 100%;
  background: #0274be;
  transition: all .35s;
}

.button:hover{
  color: white;
  text-decoration: none;
}

.button:hover:after{
  width: 100%;
}