main {
    display: grid;
    grid-template-rows: 250px auto;
    width: 100%;
}

.page-header {
    margin: 0;
    line-height: 282px;
    text-align: center;
    color: white;
    text-transform: uppercase;
    text-shadow: 2px 2px black;
}

@media only screen and (min-width: 768px) {
    main {
        grid-template-rows: 400px auto;
    }

   .page-header {
       line-height: 400px;
       font-size: 3em;
   }
}