functions.php

<?php

add_action( 'genesis_meta', __NAMESPACE__ . '\\remove_redundant_markup' );
/**
 * Remove the redundant .site-inner and .content-sidebar-wrap markup.
 *
 * @since 1.0.0
 */
function remove_redundant_markup() {

	// Remove .site-inner everywhere.
	add_filter( 'genesis_markup_site-inner', '__return_null' );

	// Remove .content-sidebar-wrap only when we're using full width content.
	if ( 'full-width-content' === genesis_site_layout() ) {
		add_filter( 'genesis_markup_content-sidebar-wrap', '__return_null' );
	}
}