It looks good from a quick overview, but a look in the code base makes me question if I'd be able to use it in a React project. For example, here:

https://github.com/htmlstreamofficial/preline/blob/bffc8d03d...

The dropdown component binds click/mousemove/keydown event handlers on the document element, but there's no method to remove such handlers. So the component does not seem to support unmounting. Also, throughout the code there are direct DOM manipulations, which I suppose are unavoidable but I would have preferred more "headless" components with no behaviors (or at least separate and more generic).