body {
  background-image: lightblue;
  text-align: center;
}
.Rojo {
    float: left;
    margin-left: 7%;
    margin-right: 2%;
}
.Verde {
    float: left;
    margin-right: 2%;
}
.Azul {
    float: left;
    margin-right: 2%;
}

.Gris {
    float: left;
    margin-right: 2%;
}
.imagenes{
  background-image: url(fondo.jpg);
  background-size: cover;
  column-count: 2;
  margin-top: 3%;
  text-align: center;
  column-rule-style: double;
  column-rule-color: pink;
  margin-right: 50%;
}