When i do my hamburger menus i do it like this..

I have a hidden checkbox for the drop down menu..

Then the hamburger menu is set as display:none until about 56em for the media css then it it is set to display: block

So what happens is that when you click the menu, the hidden checkbox is checked and the menu drops down, when you click it again, it hides it again.  But its only active below 56em which i find to be about standard size for most portables. 

Now as far as oxwall im sure its something similar even though its a static overflow menu. How did you search, did you use a file search utility like agent ransack (what i use) or even atom (its good too)  or did you just look manually.. 

If you did so manually then its worth it to use a utility to search whole scripts for a word, search for the css phase and it will show you every occurance of it.. That will save you tons of time, and then just work your way up the chain...  I also look for lang value keys as well using the same utility, that will tell me what files the lang is called in.

I could not find a ow_menu_more_active but i did find ow_menu_more

base.css 

lines

1025

1031

1041

1042

1052

1058

1064

1067

1079

1097

1104

and in  responsive_menu.html   in ow_system_plugins/base/views/components

lines

13

14

15

16

hope that helps :)

Some javascript is adding "ow_main_menu_more_active" to the ow_menu_wrap ow_responsive_menu DOM after a breakpoint and i cannot find it. I a searching the whole application via shell