[Feature request]: Allow custom theme `variant` definitions

[braswelljr]

What feature would you like to see?

Thank you for this great tool.

Allow definition of custom themes for apps looking to add more theme variants.

For instance using tailwindcss a dark theme can be set using dark:[className] with custom theme it can be set like dark-solarized:[className]. I have been trying to see if there are more ideas on setting multiple theme variants from next-themes than the defaults so there wouldn't be a need to build different contexts with complexities.

[trm217]

You can define arbitrary themes by just setting the themes property on the ThemeProvider. If you wan't auto light and dark-mode to work.
I believe the value property on the ThemeProvider might allow implementing what you're asking, as you can provide custom mappings from theme value to attribute / class value with it.
See the documentation here.