That’s a feature that ensures the format (post width, fonts, etc…) of the post being written looks the same on both back-end and front-end. If you want to turn that feature off you can do so by checking this option:
Frontier Options -> Misc -> Disable Editor Style
btw, i love your new theme – Test Project…
Thanks, I just started using it yesterday. I’ll need to tweak it some more before I share it on wordpress.org