Hi Zovi,
Because, you assign that mobile menu to 'position-1' position which displays the menu when click the original hamburger button so when you hide this button, there is nothing to show.
I just create a new position called mobile-pos >> load this position to the file: ja_simpli/index.php:
<jdoc:include type="modules" name="mobile-pos" style="raw" />
Then assign mobile menu module to this new position + add the custom CSS suggested by teitbite to 'custom.css' file again.
You can see it's showing fine now.
Regards
