At least if the user hasn't taken a screenshot the open screenshots button just silently fails.
Instead it should show a warning popup that the folder doesn't exist and suggest taking a screenshot and then trying again.
The same probably also applies to the browse saves folder button so that should also have a warning popup, and suggesting the player to make a save first.

I think it's fine to

Currently it looks like that:

We could use a UI theme there. I'd also rather use styleboxes and piggyback on button and similar nodes than use custom textures.

Currently the game comes with one card back. I'd like to have more options. In fact I'd like this to be one of the easiest things to contribute, without necessarily needing heavy coding experience.

All that is needed to contribute a new card back is to create a new scene which is a panel and modify its contents to your hearts content. The scene will be instanced on its own as the card back so i

Describe the problem or limitation you are having in your project:
To make pull requests more consistent, we should provide a pull request template.

Describe how this feature / enhancement will help you overcome this problem or limitation:
It directly related to #11 but can be done separately.

**Show a mock up screenshots/video or a flow diagram explaining how your proposal will wo