<div class="container">
  <a class="btn btn-1">Hover me</a>
  <a class="btn btn-2">Hover me</a>
  <a class="btn btn-3">Hover me</a> 
  <a class="btn btn-4">Hover me</a> 
  <a class="btn btn-5">Hover me</a>
</div>

/* <- Demo Stuff Start */

body{
  font-family: 'Montserrat', sans-serif;
  margin:0;
}

.container {
  display: flex;
  justify-content: center;
  align-items: center;
  align-content: center;
  flex-wrap: wrap;
  width: 80vw;
  margin: 0 auto;
  min-height: 100vh;
}
.btn {
  flex: 1 1 auto;
  margin: 10px;
  padding: 30px;
  text-align: center;
  text-transform: uppercase;
  transition: 0.5s;
  background-size: 200% auto;
  color: white;
 /* text-shadow: 0px 0px 10px rgba(0,0,0,0.2);*/
  box-shadow: 0 0 20px #eee;
  border-radius: 10px;
 }

/* Demo Stuff End -> */

/* <- Magic Stuff Start */

.btn:hover {
  background-position: right center; /* change the direction of the change here */
}

.btn-1 {
  background-image: linear-gradient(to right, #f6d365 0%, #fda085 51%, #f6d365 100%);
}

.btn-2 {
  background-image: linear-gradient(to right, #fbc2eb 0%, #a6c1ee 51%, #fbc2eb 100%);
}

.btn-3 {
  background-image: linear-gradient(to right, #84fab0 0%, #8fd3f4 51%, #84fab0 100%);
}

.btn-4 {
  background-image: linear-gradient(to right, #a1c4fd 0%, #c2e9fb 51%, #a1c4fd 100%);
}

.btn-5 {
  background-image: linear-gradient(to right, #ffecd2 0%, #fcb69f 51%, #ffecd2 100%);
}

/* Magic Stuff End -> */

// You can change the directon of the background change in the :hover state. Don't forget to then also change the background-color direction in the button itself. Let me know if you need any help.