.height_chang{
  display:none;
}
@media screen and (max-width: 640px){
.height_chang{
  display:block;
  height:30px;
}
.button--secondary{
  font-size:90%;
}
}
@media screen and (max-width: 320px){
.height_chang{
  display:block;
  height:30px;
}
.button--secondary{
  font-size:73%;
}
.button--primary{
  font-size:90%;
}
}