Right-to-left writing direction in epub

Hi all, would anyone know if koreader supports chinese/japanese epub format with writing direction from right to left?

I tried experimenting with modifying epub.css to have

html {
writing-mode: vertical-rl;
-webkit-writing-mode: vertical-rl;
-epub-writing-mode: vertical-rl;
}

and then set rendering style to point to it. But no luck...

Otherwise, if any one can point me to any posts in the past if it's been asked before, it would be very much appreciated as well!

Thanks a lot in advance!

Cheers,
Albert