*{
  box-sizing: border-box;
}

body{
  font-family: 'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
  line-height: 1.6em;
}

.contenedor{
  max-width: 960px;
  margin: 50px auto;
  /* text-align: center; */
}

.caja{
  background: rgb(173, 220, 173);
  color: black;
  padding: 20px;
  margin-bottom: 10px;
}

.caja h3{
  text-align: center;
}

/* .caja p{
  text-align: right;
} */


#caja2{
  float: left;
  width: 68%;
}

#caja3{
float: right;
width: 30%;
}

#caja4{
  background: blue;
}

.clear_fix{
  clear: both;
}