.box {
  width: 150px;
  height: 150px;
  background: goldenrod;
  margin-top: 20px;
  margin-left: auto;
  margin-right: auto;
  transition-delay: 2s;
}

.box:hover {
  background-color: blue;
  cursor: pointer;
}

.uni {
  transition-duration: 1s;
  transition-property: background-color;
}