.box-fisso {
   position: fixed;
   top: 500px;
   left: 50px;
   width: 200px;
   height: 200px;
   background-color: #f00;
   color: #fff;
}

.gabbia {
	position: fixed;
	bottom: 0px;
	right: 0px;
	padding: 10px;
	margin: 5px;
	'width: 25%;
}