gnab/remark ? reverse-engineered prompt

Build me a simple browser based slideshow app where I can write my slides in Markdown and see them turn into a presentation instantly.

I want to be able to paste or edit the slide content in an HTML page, refresh the browser, and have the deck render nicely with support for headings, lists, code blocks, and speaker notes. It should include a presenter view with a cloned screen, a way to move through slides with the keyboard and on touch devices, and some basic help controls. Please make the slides scale so they look good on different screen sizes, and add syntax highlighting for code. It would be great if I can also customize the look with my own CSS and simple templates for slides.

If anything is unclear, look up current docs online if you need to, then build the simplest version that works well and feels polished.