Some of the config settings don't work well with the clean theme. Some others don't work
without the clean theme. It would be better to remove the following config options and
have each of these elements tied to the over all 'theme' of the sidebar for consistency:
disableToolbarCloseBtn
disableToolbarMinimizeBtn
disableToolbarHighlightsBtn
disableToolbarNewNoteBtn
disableBucketBar
enableSidebarDropShadow
enableCleanOnboardingTheme

See https://github.com/hypothesis/product-backlog/issues/380