.btn-group{
  display:block; 
 height: 100%;
  margin-top: 20px;
 
}

button {

  background-color: #04AA6D;
  color: #ffffff;
  border: none;
  padding: 10px 20px;
  font-size: 17px;
 border-radius: 20px;
  cursor: pointer;
  font-family: 'Exo 2';
}

button:hover {
  opacity: 0.8;
}

#prevBtn {
  background-color: tomato;
}