Add data binding to inputs which change theme styles

[ilikeprograms]

For example, in the example-src files, make the editor components bind to the variables which they edit.

I should expose this through some form of API.

Either directly by adding data-* attributes to inputs, or by padding through a series of id/classes and their associated variables. Then making sure the associations are bound!

Also when theme.json files are loaded, update the editor components to reflect the variables.