Wordpress Parent-Child Pages Menu - background hig

问题:

I'm a beginner on the webdesign and coding area, so please bear with me as I try to make some sense in this question. So, I'm learning wordpress and trying to understand why some stuff is happening in a theme developed on school. The thing is: the sidebar menu, as you will see in the images, were done by a parent-child page system inside wordpress, and not by the menu tab on the appearance tab, where you can click and drag the pages and just activate the widget later.

how the menu is acting while hovering over the list parent-child:

As I'm trying to understand a bit more of what is happening, I have googled some things about this, but I still can't make much of what I learned. Anyway, I tried some things, but I'm still not there:

I tried taking the background hover from the list, and letting only the hover on a to work:

It kinda helps on what it was supposed to do, to highlight only the child item, and not the whole list, but the idea was to make the background hover to extend itself to the whole space that the "container" of that line's content have, just like it shows in the right part of the image_02. Now, would that be possible? In this case, would I have to get the parent highlighted as well, and not only one child at time? Or I can't get this result with this parent-child pages menu system?

Here's the site, in case you would like to have a look: http://dadin.ct.utfpr.edu.br/

Sorry if this sounds kinda confusing, but thanks in advance anyways!