/',
			$link,
			$output,
			1 // Limit.
		);

		// replace closing </a> with </span>
		$output = preg_replace(
			'#</a>#i',
			'</span>',
			$output,
			1 // Limit.
		);

	} elseif ( in_array( 'menu-item-has-children', $item->classes, true ) ) {

		// Add SVG icon to parent items.
		$icon = twentynineteen_get_icon_svg( 'keyboard_arrow_down', 24 );

		$output .= sprintf(
			'<span class="submenu-expand" tabindex="-1">%s</span>',
			$icon
		);
	}

	return $output;
}
//add_filter( 'walker_nav_menu_start_el', 'twentynineteen_add_dropdown_icons', 10, 4 );

/**
 * Create a nav menu item to be displayed on mobile to navigate from submenu back to the parent.
 *
 * This duplicates each parent nav menu item and makes it the first child of itself.
 *
 * @param array  $sorted_menu_items Sorted nav menu items.
 * @param object $args              Nav menu args.
 * @return array Amended nav menu items.
 */
function twentynineteen_add_mobile_parent_nav_menu_items( $sorted_menu_items, $args ) {
	static $pseudo_id = 0;
	if ( ! isset( $args->theme_location ) || 'menu-1' !== $args->theme_location ) {
		return $sorted_menu_items;
	}

	$amended_menu_items = array();
	foreach ( $sorted_menu_items as $nav_menu_item ) {
		$amended_menu_items[] = $nav_menu_item;
		if ( in_array( 'menu-item-has-children', $nav_menu_item->classes, true ) ) {
			$parent_menu_item                   = clone $nav_menu_item;
			$parent_menu_item->original_id      = $nav_menu_item->ID;
			$parent_menu_item->ID               = --$pseudo_id;
			$parent_menu_item->db_id            = $parent_menu_item->ID;
			$parent_menu_item->object_id        = $parent_menu_item->ID;
			$parent_menu_item->classes          = array( 'mobile-parent-nav-menu-item' );
			$parent_menu_item->menu_item_parent = $nav_menu_item->ID;

			$amended_menu_items[] = $parent_menu_item;
		}
	}

	return $amended_menu_items;
}
add_filter( 'wp_nav_menu_objects', 'twentynineteen_add_mobile_parent_nav_menu_items', 10, 2 );

/**
 * Convert HSL to HEX colors
 */
function twentynineteen_hsl_hex( $h, $s, $l, $to_hex = true ) {

	$h /= 360;
	$s /= 100;
	$l /= 100;

	$r = $l;
	$g = $l;
	$b = $l;
	$v = ( $l <= 0.5 ) ? ( $l * ( 1.0 + $s ) ) : ( $l + $s - $l * $s );
	if ( $v > 0 ) {
		$m;
		$sv;
		$sextant;
		$fract;
		$vsf;
		$mid1;
		$mid2;

		$m = $l + $l - $v;
		$sv = ( $v - $m ) / $v;
		$h *= 6.0;
		$sextant = floor( $h );
		$fract = $h - $sextant;
		$vsf = $v * $sv * $fract;
		$mid1 = $m + $vsf;
		$mid2 = $v - $vsf;

		switch ( $sextant ) {
			case 0:
				$r = $v;
				$g = $mid1;
				$b = $m;
				break;
			case 1:
				$r = $mid2;
				$g = $v;
				$b = $m;
				break;
			case 2:
				$r = $m;
				$g = $v;
				$b = $mid1;
				break;
			case 3:
				$r = $m;
				$g = $mid2;
				$b = $v;
				break;
			case 4:
				$r = $mid1;
				$g = $m;
				$b = $v;
				break;
			case 5:
				$r = $v;
				$g = $m;
				$b = $mid2;
				break;
		}
	}
	$r = round( $r * 255, 0 );
	$g = round( $g * 255, 0 );
	$b = round( $b * 255, 0 );

	if ( $to_hex ) {

		$r = ( $r < 15 ) ? '0' . dechex( $r ) : dechex( $r );
		$g = ( $g < 15 ) ? '0' . dechex( $g ) : dechex( $g );
		$b = ( $b < 15 ) ? '0' . dechex( $b ) : dechex( $b );

		return "#$r$g$b";

	} else {

		return "rgb($r, $g, $b)";
	}
}