.inicio{
	background-image: url(../../imagen/b1.jpg);
	background-position: center center;
	background-repeat: no-repeat;
	background-attachment: fixed;
	background-size: cover;
	background-color: #fff;
}
.centrar{
 	position: absolute;
  	top:50%;
  	left:50%;
  	width:400px;
  	margin-left:-200px;
  	height:300px;
  	margin-top:-150px;
  	padding:5px;
}
@media only screen and (max-width: 1200px) {
	.inicio{
		background-image: url(../../imagen/b1.jpg);
		background-position: unset;
	}
}
@media only screen and (max-width: 768px) {
	.inicio{
		background-image: url(../../imagen/b3.jpg);
		background-position: unset;
	}
}
@media only screen and (max-width: 425px) {
	.inicio{
		background-image: url(../../imagen/b3.jpg);
		background-position: unset;
	}
}