aggiungi una regola del tipo:
codice HTML:
input{
      -webkit-transition: all 0.7s ease-out;
      -moz-transition: all 0.7s ease-out;
      -ms-transition: all 0.7s ease-out;
      -o-transition: all 0.7s ease-out;
      transition: all 0.7s ease-out;
}