@media (min-width: 768px) {
    #page-content {
        background: url(../Images/404.jpg) no-repeat top center;
        background-size: cover;
    }

    #not-found-container {
        margin-left: 50%;
        background: rgba(0,0,0,0.4);
        width: 450px;
        padding: 40px;
        color: #FFF;
        margin-top: 50px;
    }

    #not-found-container a:hover, #not-found-container a:link, #not-found-container a:focus, #not-found-container a:active, #not-found-container a:visited {
        color: #FFF;
    }
}