.mobile {
    width: 200px;
}

@media (max-width: 800px) {
    /* CSS that should be displayed if width is equal to or less than 800px goes here */

    .web {
        width: 1000px;
        margin: 0 auto;
    }

    .mobile {
        width: 200px;
        margin: 0 auto;
    }

    .mobile-landscape {
        width: 1000px;
        margin: 0 auto;
    }

}


.web {
    width: 1000px;
}