*{box-sizing: border-box; margin: 0; padding: 0;}
.contenedor{margin: auto;}

header {
    background-color: #03b403; 
    padding:2rem;}

main {
    background-color: #290098; 
    padding:0.2rem; 
    max-width:100%;display: 
        flex;justify-content:space-between;}

.articulos {
    column-count: 3; 
    display:block; 
    justify-content:space-around; 
    background-color: #9cb2fa; 
    padding:1rem; 
    width:70%;
    margin:0.5rem;}

.articulos article {
    background: #000; 
    padding:6rem; 
    margin:0 0 1rem 0;}

main aside{
    background-color: #8b8b8b; 
    width:30%; padding:1rem; 
    margin:0.5rem;}

footer{
    background-color: #176d02; 
    padding:4rem;}