image hover transition in out

.btn {
  background-color: #ddd;
  color: black;
  transition: 0.3s;
}

.btn:hover {
  background-color: #3e8e41;
  color: white;
}

/* Simple CSS color transition effect on selector */

div {
	color: white;
  	background-color: black; 
}

div:hover {
	background-color: red;
}


/* Additional transition effects on selector */

div {
	background-color: black;
  	color: white;
  	height: 100px;
  	transition: width 1.5s, height 3s;
  	width: 100px;
  	
}

div:hover {
	background-color: red;
  	height: 300px;	
  	width: 150px;
}
  

#cf {
  position:relative;
  height:281px;
  width:450px;
  margin:0 auto;
}

#cf img {
  position:absolute;
  left:0;
  -webkit-transition: opacity 1s ease-in-out;
  -moz-transition: opacity 1s ease-in-out;
  -o-transition: opacity 1s ease-in-out;
  transition: opacity 1s ease-in-out;
}

#cf img.top:hover {
  opacity:0;
}