I started using Grommet, it is really awesome library, so I recommend it if you have not chosen one. But I would like to ask, why FB itself does not provide one? For now, they seem to provide only the hammer and nails which is not the customers (IMO) are looking for. For me it would be great if they provide css, components and provide decent support. For now we have dozens of UI libraries, which are too risky to use as the support may not be at acceptable level. Anyone from FB could comment?