Add missing StyleRules modules

a74367c deleted CSS files in favor of using react-styles to manage styling, but didn't add the necessary style modules or define them in packages.json. This fixes the "requiring unknown module" error, and reimplements the same visual style from before. Note: styles may not be applied correctly due to the use of Unicode in the react-styles namespacing, see https://github.com/hedgerwang/react-styles/pull/1