Theme editor to store, select and customize a theme

Default themes and preset should be saved in the Layouts (tbd) and the active preset theme should be stored in the Shops collection as theme.

Editing / saving should always be stored in the Layouts collection before the act of "publishing" to Shops (as the generated CSS theme).

Admin user should be able to preview their theme changes from the Layout collection, before activating it (by moving to Shops collections).

Admin user should be able to edit or clone, delete themes.

Proposed structure:

themes: [ {
    name:  "base",
    theme:  [{
        [selector]: {
            [background]: "#fff"    
        }
    }]
}]

or the as a "free style" object;

Style.registerRule('@media print', {
  body: {
    color: 'red'
  }
})

Add https://atmospherejs.com/juliancwirko/postcss

These entries will get looped with PostCSS, and create post css freestyle rules, that are applied to the site styling.