* { box-sizing: border-box< margin: 0; padding: 0 }
.contenedor {max-width: 75rem; margin: auto; }
header {width: 100%; background: #ffb2bf; height: 10rem; }
nav { width: 100%; background: red; height: 4rem; }
section {background: blue; display: flex; justify-content: space-around; }
section article {width: 45%; background: orange; height: 20rem; margin: 3rem 0 3rem 0; }
aside { background: #ddd; display: flex; justify-content: space-around; }
aside .ancho65 { background: #00ffb1; height: 15rem; width: 65%; margin: 2rem 0; }
aside .ancho30 { background: #d800ff; height: 15rem; width: 30%; margin: 2rem 0; }
footer { width: 100%; background: green; height: 4rem; }