I checked the CSS to see where I missed exactly. When I flipped the image, I also flipped the positions of the arrows themselves. So the CSS had to be changed.
Another solution is to flip the arrows themselves in the image and not their positions. I've updated the package with the updated arows-ffffff-rtl.png
Easier solution
I checked the CSS to see where I missed exactly. When I flipped the image, I also flipped the positions of the arrows themselves. So the CSS had to be changed.
Another solution is to flip the arrows themselves in the image and not their positions. I've updated the package with the updated arows-ffffff-rtl.png
Thanks again for the tip :)