Is there a way to duplicate a style within a theme?

I want to differentiate groups of tiles by border color. Since there isn’t an easy way to simply change the border color of a tile (that I know of), I’m having to create a new style for each border color. The problem with that is, I have to set all the other attributes every time.

1). It would be much better if each new style started with the attributes of the first defined style, rather than the app default (blue background, etc). Then just add whatever attributes you wanted to change. In my case, I would only need to add border color.

2). If I could duplicate an existing style, even better. Then I just change the border color.

Is there anything currently in place that will let me accomplish this, or am I going to have to create a new style from scratch every time I need a new border color?