Allow for flex height (full height)

[luap2703]

Currently the height property only allows for fixed numbers. It would be good to have it also accept other valid height string values, i.e., "100%", "auto", etc.

Current workaround requires: height={"100%" as unknown as number}

Also, the inner-container (the div inside dsg-container) has no selector/classname. It would be great if this one could also get a classname to adjust css of it as well.

Anyway, great lib!