.primero{
  background-color:red;
  height:50px;
  width:150px;
  color:black;
  float:left;}
  .segundo{
  background-color:green;
  color:black;
  height:50px;
  width:150px;
  float:left;
  }
   .tercero{
  background-color:blue;
  height:100px;
  width:60%;
  float:left;
   }
   .cuarto{
  background-color:grey;
  color:black;
  height:150px;
  width:30%;
  float:left;}