Migrate to fomantic themes

[olgamie]

The slider is not supported by Semantic themes and we should migrate to Fomantic themes to be able to support this component.

After this is implemented theme selector should be added (uncommented) in the examples/app.R (check TODO comments).
Please remember to update the example description in readme (add information about theme change) and deploy app to Rstudio connect.

[andrie]

Do you have hints on where to start with this work? For example, is there any background reading on how fomantic themes differ from semantic ui themes? Where would one download fomantic specific themes? Are the themes at https://semantic-ui-forest.com/ still valid?

[dokato]

Thanks @andrie for trying to help. Sorry if this wasn't clear. This is one reading I'm aware of: https://fomantic-ui.com/usage/theming.html,

There is no Fomantic equivalents of cerulean etc. to my knowledge. As you can see more people had troubles with that: semantic-ui-forest/forest-themes#52

So the first step would be to identify the components that break, and what's needed to fix them quickly. I think that the best starter would be this example:
https://github.com/Appsilon/shiny.semantic/tree/develop/examples/customcss
and copying there as custom css one of the semantic forest themes and check what does and what doesn't work.

Eg. in this app https://github.com/Appsilon/shiny.semantic/blob/develop/examples/app.R there's almost full list of components covered.