How did I create a custom theme?

Hi.

I was editing
\modules\mod_maximenuck\themes\css3megamenu\css\maximenuck.php
when i noticed that my changes were not taking effect. when inspecting the code on the page I noticed that the styles were comming from
\modules\mod_maximenuck\themes\custom\css\maximenuck_maximenuck343.css

How did this custom theme get created? Was it something I did in the Joomla back end? Can I remove it and go back to making style changes to the maximenuck.php file?

Hi
this is because you have activated the option "compile css" to "yes", you can set it on no or on "compile" to recreate the file on every page load
CEd