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


/* estructura */
.contenedorrosa{ width: 100%;background: pink; }
.contenedorrojo{ width: 100%;background: red; }


header{ background: pink; height: 10rem; display: flex; justify-content: space-between; align-items: center; width: 100%; max-width: 80rem; margin: auto;}

.logo{ display: block; width: 5rem; height: 5rem; background: white;}
header nav{ width: 5rem; height: 2rem; background: grey;}


section{ width: 100%; max-width: 80rem; margin: auto;}
section article{ width: 100%; height: 100vh; background: #ddd; padding: 5rem;}
section article img{ width: 50%; display: block; margin: auto;}

@media all and (min-width:35rem){
    section{ display: flex;}
    section article{  background: #f00; width: 50%;}
    
}