body{
}
.bloc1 {
	width:300px;
	height:800px;
	background-color:#000000;
	float:left;
	opacity:1;
}
.bloc2 {
	width:300px;
	height:800px;
	background-color:#FFFF00;
	
	margin-left:60px;
	opacity:0.5;

}
.bloc3 {
	width:300px;
	height:800px;
	background-color:#FF0000;
	float:left;
}