Moving secondary sidebar inside Content Sidebar wrap and replacing floats with Flexbox in Genesis

In Genesis Slack chat a user asks:

I would like to move the secondary sidebar into the content sidebar wrap, so I have sidebar/content/sidebar within the wrap. Nothing I’ve tried so far seems to work. Any help would be most appreciated.

By default, the secondary sidebar is present outside div.content-sidebar-wrap in Genesis 2.5.3.

By adding

remove_action( 'genesis_after_content_sidebar_wrap', 'genesis_get_sidebar_alt' );
add_action( 'genesis_after_content', 'genesis_get_sidebar_alt' );

in child theme’s functions.php, .sidebar-secondary can be moved inside .content-sidebar-wrap.

Let’s now replace the floats with Flexbox in CSS for the display of Content/Sidebar/Sidebar, Sidebar/Sidebar/Content and Sidebar/Content/Sidebar layouts.

While the tutorial has been written for Genesis Sample 2.3.0, it should work with a few adjustments in any Genesis theme.

Edit style.css.

a) Above the media queries add

.content-sidebar-sidebar .content-sidebar-wrap,
.sidebar-content-sidebar .content-sidebar-wrap,
.sidebar-sidebar-content .content-sidebar-wrap,
.content-sidebar-sidebar .content,
.sidebar-content-sidebar .content,
.sidebar-content-sidebar .sidebar-primary,
.sidebar-sidebar-content .sidebar-primary,
.content-sidebar-sidebar .sidebar-primary,
.sidebar-secondary {
    float: none;
}

.content-sidebar-sidebar .content-sidebar-wrap,
.sidebar-content-sidebar .content-sidebar-wrap,
.sidebar-sidebar-content .content-sidebar-wrap {
    width: auto;
}

@media only screen and (min-width: 1024px) {
    .content-sidebar-wrap {
        display: flex;

        justify-content: space-between;
    }

    /* Sidebar/Sidebar/Content */

    .sidebar-sidebar-content .sidebar-secondary {
        order: 0;
    }

    .sidebar-sidebar-content .sidebar-primary {
        order: 1;
    }

    .sidebar-sidebar-content .content {
        order: 2;
    }

    /* Sidebar/Content/Sidebar */

    .sidebar-content-sidebar .sidebar-secondary {
        order: 0;
    }

    .sidebar-content-sidebar .content {
        order: 1;
    }

    .sidebar-content-sidebar .sidebar-primary {
        order: 2;
    }
}

b) In the 1340px media query, comment out or delete

.content-sidebar-sidebar .content-sidebar-wrap,
.sidebar-content-sidebar .content-sidebar-wrap,
.sidebar-sidebar-content .content-sidebar-wrap {
    width: 920px;
}

c) In the 1200px media query, comment out or delete

.content-sidebar-sidebar .content-sidebar-wrap,
.sidebar-content-sidebar .content-sidebar-wrap,
.sidebar-sidebar-content .content-sidebar-wrap {
    width: 740px;
}

Reference: genesis/lib/structure/layout.php