Show HN: OverType – A Markdown WYSIWYG editor that's just a textarea

Summary

Hi HN! I got so frustrated with modern WYSIWYG editors that I started to play around with building my own.The problem I had was simple: I wanted a low-tech way to type styled text, but I didn't want to load a complex 500KB library, especially if I was going to initialize it dozens of times on the same page.Markdown in a plain <textarea> was the best alternative to a full WYSIWYG, but its main drawback is how ugly it looks without any formatting. I can handle it, but my clients certainly can't.I went down the ContentEditable rabbit hole for a few years, but always came to realize others had solved it better than I ever could.I kept coming back to this problem: why can't I have a simple, performant, beautiful markdown editor? The best solution I ever saw was Ghost's split-screen editor: markdown on the left, preview on the right, with synchronized scrolling.Then, about a year ago, an idea popped into my head: what if we layered a preview pane behind a <textarea>? If we aligned them perfectly, then even though you were only editing plain text, it would look and feel like you were editing rich text!Of course, there would be downsides: you'd have to use a monospace font, all content would have to have the same font size, and all the markdown markup would have to be displayed in the final preview.But those were tradeoffs I could live with.Anyways, version 1 didn't go so well... it turns out it's harder to keep a textarea and a rendered preview in alignment than I thought. Here's what I discovered:- Lists were hard to align - bullet points threw off character alignment. Solved with HTML entities (• for bullets) that maintain monospace width- Not all monospace fonts are truly monospace - bold and italic text can have different widths even in "monospace" fonts, breaking the perfect overlay- Embedding was a nightmare - any inherited CSS from parent pages (margin, padding, line-height) would shift alignment. Even a 1px shift completely broke the illusionThe solution was obsess...