@media only screen and (min-width: 32.5em) {
    nav ul { 
        display: flex; 
    }
    nav ul li { 
        flex: 1 1 100%
     }
     main {
        grid-template-columns: 1fr;
    }
    main ul {
        display: flex;
        margin: 10px;
    }
    main ul li {
        flex: 1 1 100%
    }
}