参考サイトのようにしたい場合は下記のように追記してください。
【子テーマの functions.php 】
/**
* Change lightning_get_the_class_names Output.
*
* @param string $class_names Classes of Output.
*/
function my_lightning_get_the_class_names( $class_names ) {
if ( 'bs4' === $skin_info['bootstrap'] ) {
if ( lightning_is_layout_onecolumn() ) {
$class_names['mainSection'] = 'col mainSection col-lg-12';
$class_names['sideSection'] = 'col subSection sideSection col-lg-12';
} else {
// 2 column.
$options = get_option( 'lightning_theme_options' );
// sidebar-position.
if ( isset( $options['sidebar_position'] ) && 'left' === $options['sidebar_position'] ) {
$class_names['mainSection'] = 'col mainSection col-lg-9 order-lg-1';
$class_names['sideSection'] = 'col subSection sideSection col-lg-3 order-lg-0';
} else {
$class_names['mainSection'] = 'col mainSection col-lg-9 order-lg-0';
$class_names['sideSection'] = 'col subSection sideSection col-lg-3 order-lg-1';
}
}
}
}
add_filter( 'lightning_get_the_class_names', 'my_lightning_get_the_class_names' );
【子テーマの style.css】
.siteContent>.container>.row {
display: flex;
}