/**{margin:0;padding:0;box-sizing:border-box;}*/
body{border:1px solid blue;}

padre{display:flex;flex-direction:column; flex-wrap: nowrap;}
header{border:1px solid black;background-color:gray;}
section{border:1px solid blue;background-color:antiquewhite;}
footer{border:1px solid red;background-color:steelblue;}

.superior{background-color:palegreen;}
.inferior{background-color:lightsteelblue;}
.izquierdo{background-color:rebeccapurple;}
.centro{background-color:antiquewhite;}