styles.css

#content h4 {
    margin-top: 30px; 
}
#SiteNavBar.navbar {
    margin-bottom: 0;
}
#GridSystem .row {
    border: 1px solid orange;
}
#GridSystem .row > div {
    border: 1px solid grey;
}

/*##### MEDIA QUERIES ###### */

/* Extra small devices (phones, less than 768px) */
/* No media query since this is the default in Bootstrap */
    .media-example:after {
        font-size: 28px;
        display: block;
        content: 'XS';
        background: lightblue;
    }


/* Small devices  */
@media (min-width: 768px) {
    .media-example:after {
        content: 'SM';
        background: lightcoral;
    }

}

/* Medium devices */
@media (min-width: 992px) {
    .media-example:after {
        content: 'MD';
        background: lightgoldenrodyellow;
    }

}

/* Large devices  */
@media (min-width: 1200px) {
    .media-example:after {
        content: 'LG';
        background: lightseagreen;
    }

}