.btn 
{
  border: 2px solid;
  border-radius: 4px;
  background: transparent;
  color: black;
  font-weight: bold;
  font-size: 1em;
  cursor: pointer;
  position: absolute;
  width: 40%;
  height: 15%;
  top: 70%;
  left: 30%;  
  transition: all 0.3s ease;
}

.red 
{
  border-color: red;
  color: white
}

.red:hover 
{
  background: red;
  color: white;
}