Jetpack_Custom_CSS_Enhancements::set_content_width PHP Method

    static function set_content_width()
    {
        // Don't apply this filter on the Edit CSS page.
        if (isset($_GET['page']) && 'editcss' === $_GET['page'] && is_admin()) {
            return;
        }
        $GLOBALS['content_width'] = Jetpack::get_content_width();
    }