body{
  font-family: Helvetica;
}
.responsive {
  max-width: 100%;
  height: auto;
}
a{
  text-decoration: none;
}

.box{
  background: #50bbe6e0;
  text-align: center;
  color: #fff;
  width: 100%;
  padding: 20px 3px;
  border-radius: 10px;
  display: block;
  background-image: linear-gradient(to left, transparent, transparent 50%, #72f4fb 50%, #45a8d9);
  background-position: 100% 0;
  background-size: 200% 100%;
  transition: all .25s ease-in;

}
.box:hover{
background-position: 0 0;
color:#333;
}