Filter for woocommerce tabs? How?

Hello.
I’m changing my theme’s single-product template. I need to remove the woocommerce tabs and re-put them one below the other.
I did it with the below code:

function remove_woocommerce_product_tabs( $tabs ) {
	// var_dump($tabs);
	// var_dump($tabs['description']);
	unset( $tabs['description'] );
	unset( $tabs['reviews'] );
	unset( $tabs['additional_information'] );
	unset( $tabs['custom_editor_tab'] );
	unset( $tabs['custom_author_tab'] );
	return $tabs;
}
add_filter( 'woocommerce_product_tabs', 'remove_woocommerce_product_tabs', 98 );

add_action('thegem_woocommerce_single_product_bottom', 'woocommerce_product_description_tab', 1);
add_action('thegem_woocommerce_single_product_bottom', 'woocommerce_product_additional_information_tab', 2);
add_action('thegem_woocommerce_single_product_bottom', 'custom_author_tab_content', 3);
add_action('thegem_woocommerce_single_product_bottom', 'custom_editor_tab_content', 4);

The problem is that, now, i need to put every “tab” in a separate <div>.
I tried with this code, but is not working and i not understand why:

function alpha_test($content) {
	$start = '<div style="background-color: #000 !important;">';
	$end = '</div>';
	$final = $start . $content . $end;
	return $final;
}
add_filter('custom_author_tab', 'alpha_test');

How can i solve this?

Thank you in advance.
-Kryuko

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