.base-class {
  -webkit-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;
}

.base-class.my-class {
  color: red;
  font-size:3em;
}