@media only screen and (min-width: 37.5em) {
    header {
        width: 100% auto;
      }

    nav ul {
        display: flex;
    }
    nav ul li { 
        flex: 1 1 100%; 
    }

    footer {
        width: 100% auto;
    }

    h1 {
        font-size: 2em;
    }

    h2{
        font-size: 1.5em;
    }

    .lesson3_grid {
        grid-template-columns: 1fr 1fr;
    }

    .page-head {
        grid-column: 1/3;
    }
    
    #color1 {
        grid-row: 2;
    }
    
    #color2 {
        grid-column: 2;
        grid-row: 2;
    }
    
    #color3 {
        grid-column: 1;
        grid-row: 3;
    }

}