Edit in JSFiddle

<div class="color">
  Change Color
</div>
.color {
  margin: 40px 80px;
  width: calc(100% - 160px);
  background: #676470;
  color: #fff;
  font: 3.5em sans-serif;
  font-weight: 900;
  text-align: center;
  line-height: 300px;
  transition: background-color 1s ease-in-out;
}

.color:hover {
  background: #53a7ea;
}