.css-class-add, .css-class-remove {
    -webkit-transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;
    -moz-transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;
    -o-transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;
    transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;
  }

  .css-class,
  .css-class-add.css-class-add-active {
    color: red;
    font-size:3em;
  }

  .css-class-remove.css-class-remove-active {
    font-size:1.0em;
    color:black;
  }