The tool was under the approval queue for a couple weeks, and I was making changes during the downtime. Here's the changelist.
make skins stand out better
remove ambiguity on assignment texts
'Push stick-left to right' isn't a clear text
better deadzone decision
properly skip looking for dpad change for render when it doesn't exist in the mapping
fix Renderer getting undefined as a skin name when a new gamepad is found on a slot previously used
skipped inputs in the assignment process are properly assigned with null
I released a guide on how to make a skin on the repository wiki. As it's said in the readme, you need to host Mini Padder locally to be able to use them. Also this made changes on how skins work, which are not backward compatible. Hence the major version number increment.
some render instructions for skin are rewritten
improvements on rendering process
each button groups can choose separate layer to render