Forget about it. MiniComps are not stylable/themable.
Which is to say that you can choose a “dark theme” or a “modern theme” or make up your own theme.
They were designed very specifically to be minimal and have a single look and feel. Adding in themes would introduce a ton of complexity. It is possible to customize properties of individual components, such as text color or font size, etc. And even to pre-set defaults for certain properties of some components. But when we talk about theming, this means some kind of global theme configuration or style sheet that automatically applies to all components as they are created. Or even after they already exist.That’s very unlikey to happen.
The whole concept of MiniComps is that it’s a single file you drop in your project and use as-is. They are for creating experiments, proof-of-concept projects, or rapid prototypes. They’re not a general purpose UI kit meant for a final deliverable project. That said, if you like the way they look and want to use them as-is, that’s great!