Width of ul on the second parent (probably)???

Question

Java

I need help, the whole brain has broken,
there is already such a template - Metronik
and so, there is a menu in one of the topics:

<ul class>
   <li class>
       <ul class="class2">
           <li></li>
           <li></li>
           <li></li>                              
       </ul>
   </li>
   <li class></li>
   <li class></li>
</ul>

an approximate structure, and so, nested in li the second ul has position:absolute; and the parent li, as well as everything above, is static, but it (the second ul) takes the width of not the window, but either the second parent or h.z. Why
, when trying to make a similar menu, my ul gets out of the layout if I write to the parent static, that it is logical that
someone will be able to explain how they did it?
link to the topic - keenthemes.com/preview/metronic/theme/admin_5/inde...
there on top where there are tabs, the second submenu

Answer 1

public static void main (String[] args)

Answer 2

c2n.me/3AJV86C Everything
should be clear from the picture.
In short, the indents are set there through right: xxx and left: xxx Then it occupies the full width of the relative ancestor, taking into account the indents