body
{background-color:red;
}

div{
text-align:center;
color:beige;
font-size:50px;
}

.caja1{text-align:center;
}
.caja2{float:right;
}
.caja3{float:left;
}
.caja4{background-color:black;
      text-align:center;
      color:white;
      font-size:50px;
}