.rojo{
 height:50px;
 width:150px;
 background-color:red;
 float:left;}

.verde{
 height:50px;
 width:150px;
 background-color:green;
 float:left;}

.azul{
 height:100px;
 width:60%;
 background-color:blue;
 float:left;}

.gris{
 height:150px;
 width:30%;
 background-color:grey;
 float:left;}