I just did a quick test with your CSS, and the compiled .mobi file looked OK on my PW2 and Kindle for iOS app, but not with the Kindle for PC app.
Most likely, the Kindle for PC app uses a different rendering engine. If you want to achieve 100% compatibility, you might have to experiment with tables or other HTML elements.
BTW, the firmware of eInk Kindles does not support embedded fonts for RTL languages; RTL languages will always be rendered with the glyphs from the
code2000 fallback font. (You cannot see this in my screen capture, because I installed a font override that uses the Hebrew glyphs from Arial.)