img {
  width: 300px;
}


.bgImgDefault {
  width: 300px;
  aspect-ratio: 1/1; /* https://caniuse.com/mdn-css_properties_aspect-ratio */
  background-size: cover;
}

.cssBackgroundImg {
  background-image: url(../img/cat-01.jpg);
}
.cssBackgroundImg:hover {
  background-image: url(../img/cat-02.jpg);
  cursor:crosshair;
}