@keyframes nez {
  0% {
    background-image: url('../img/fissures.png');
  }
  /* Adding a step in the middle */
  50% {
    background-image: url('../img/nez-petit-gris.png');
  }
  100% {
    background-image: url('../img/nez-21.png');
  }
}
@keyframes nez-gris {
  0% {
    background-image: url('../img/fissures-gris.png');
  }
  /* Adding a step in the middle */
  50% {
    background-image: url('../img/nez-petit-gris-fond-gris.png');
  }
  100% {
    background-image: url('../img/nez-fond-gris.png');
  }
}
@keyframes nez-rouge {
  0% {
    background-image: url('../img/fissures-rouge.png');
  }
  /* Adding a step in the middle */
  50% {
    background-image: url('../img/nez-petit-gris-fond-rouge.png');
  }
  100% {
    background-image: url('../img/nez-fond-rouge.png');
  }
}