MediaWiki:3colmainpage.css

/* This CSS governs the responsive 3 column main page layout */
.fpmidsections {
    float: left;
    width: 100%;
    overflow: hidden;
}

.fpsection1,
.fpsection2,
.fpsection3,
.fpsection4 {
    float: left;
    clear: both;
    width: 100%;
}

.fpmain .columns .leftcol,
.fpmain .columns .rightcol {
    width: 100%;
    margin: 0;
    padding: 0;
}

@media (min-width: 790px) {
    .fpsection1,
    .fpsection4 {
        float: left;
        clear: none;
        width: 50%;
    }

    .fpmidsections {
        float: right;
        clear: none;
        width: 50%;
    }
}

@media (min-width: 990px) {
    .fpmain .columns .leftcol {
        float: left;
        width: 50%;
    }

    .fpmain .columns .rightcol {
        float: right;
        width: 50%;
    }
}

@media (min-width: 1390px) {
    .fpmidsections {
        clear: none;
        float: right;
        width: 66.667%;
    }

    .fpsection1 {
        clear: none;
        width: 33.333%;
    }

    .fpsection2,
    .fpsection3 {
        clear: none;
        width: 50%;
    }

    .fpsection4 {
        clear: left;
        width: 33.333%;
    }
}