you may store custom css in portal.css file or any css/JS in individual skin folder or any custom subfolder folder inside /desktopmodules or /providers

Thanks a lot, Sebastian Leupold 

Is it bad to store custom files in the Resources folder? is there any chance that it can be overwritten when we upgrade DNN?

Not necessarily a bad idea, but there are probably better places to store custom files. And the answer to "where" depends on the intended purpose of the custom files. What is the use of the files?

thanks, Joe Craig

Idea is to create a common module for all shared static resources.

These are CSS/JS shared files across the portals, which we want to put in the Resources folder through the install package.

I'd probably use a custom folder, and I'd also probably put it in Portals/_default to make sure that it's more accessible to the Global Assets manager.

/Resources is usually kept for DNN system resources and common JS libraries (installed by DNN), like jQuery and Knockout.
Resources, you need for your custom extensions, should be placed in /desktopmodules/ or /providers/ subfolder, preferably using an individual name prefix or all stored in subfolders of a company folder, like /desktopmodules/mycompany/mymodule/ or /desktopmodules/mycompany/shared/. This convention prevents name conflicts and your libraries are easily identificable.
For design files, DNN uses for historical reasons subfolders inside /portals/_default/skin/, /portals/_default/container/, /portals/[portalid]/skin and /portals/[portalid]/container. these are the best places for most of your visual resources, which are not tight to functional extensions. Have a look at existing folder structures of modules and themes included with DNN or availaible on this site or in the store.
Just ask, if you still are having any questions :)

Posted By Jasbir on 06 Apr 2021 02:09 PM

thanks, Joe Craig

Idea is to create a common module for all shared static resources.

These are CSS/JS shared files across the portals, which we want to put in the Resources folder through the install package.

As long as you use a unique path, these will not be overwritten.
BTW, you can create a package just for installing resources.

https://www.dnnsoftware.c...sourcefile-component

 

 

There is also a module for that I use quite often: Will Strohl's Content Injection, available here: github.com/hismightiness/dnnextensions. The current release can be found here.

Happy DNNing!
Michael