Kundi za Madarasa katika CSS

Acha tuwe na madarasa kadhaa ambayo huwaweka vipengele kwa rangi tofauti:

css.xxx {
  color: green;
}
.yyy {
  color: red;
}

Acha tunataka kufanya ili madarasa haya zaidi ya rangi, pia weka ukubwa wa herufi:

css.xxx {
  color: green;
  font-size: 30px;
}
.yyy {
  color: red;
  font-size: 30px;
}

Kwa kuwa madarasa yote mawili yanaweka ukubwa sawa wa herufi, wacha tutumie kundi za wachaguzi kama ifuatavyo:

css.xxx {
  color: green;
}
.yyy {
  color: red;
}

.xxx, .yyy {
  font-size: 30px;
}

css.eee {
  font-size: 20px;
  line-height: 1.5;
  font-family: Arial;
}
.zzz {
  font-size: 30px;
  line-height: 1.5;
  font-family: Arial;
}

css.eee {
  font-size: 20px;
  text-align: center;
  font-family: Arial;
}
.zzz {
  font-size: 30px;
  text-align: center;
  font-family: Arial;
}
.ggg {
  font-size: 35px;
  text-align: center;
  font-family: Arial;
}