Allows add-ons to easily override the theme, and allows us to apply
styling to elements outside of the normal document flow (like applying
the normal background colour to a position: fixed element).
- blue for normal sync, red for full sync required
- refactor status fetching code so we don't hold a collection lock
during the network request, which slows things down
- fix sync spinner restarting when returning to deck list
Forces the Fusion theme when running night mode, so we don't need
to work around platform themes that don't respond to the defined
palette.
Feedback/suggestions on the chosen colours welcome - _vars.scss is the
file to change if you want to experiment with adjustments.
