Haha, that would be a disaster!

However, I have just posted one post on the platform yet, and for that, I used this platform called StackEdit. https://stackedit.io/

The good news is, you don't have to know any Markup techniques, you have buttons to do all the formatting. Moreover, it saves the posts for future reference. And once you are done writing, simply copy the whole content, paste into Steemit and hit the Post button. Highly recommended!