3rd level navigation for bootstrap_package?

Hello,

I have used the sitepackage builder to create a bootstrap site package. I noticed that I can see 2 levels of the horizontal menu while my page hierarchy has more. I discovered that if I set page.10.dataProcessing.10.levels = 3
it brings successfully the 3rd level children data (I see this using the
<f:debug title="mainnavigation">{mainnavigation}</f:debug>
added in the layout file. But of course they were not rendered anywhere.

I found some help here midide/typo3-v10.4-mulitlevelmenu: TYPO3 v10.4 Multi-Level Menu with MenuProzessor, jQuery v3.5, Bootstrap v4.5, SmartMenus v1.1 (github.com) and implemented those changes in my site package but while now the HTML contains the new 3rd level items (I can see the source of the page having the new ul and li’s, they don’t appear anywhere.

Does it seem like a CSS issue?

Ok, I made it work following these instructions: Ready-made TYPO3 menus! | copy & paste | with demo :: S. Klein (sebkln.de)