Write to up@dowwwn.com: a question, a page that doesn't look right (send its address), an idea. We answer.
Pages written in Markdown, and only those: .md files on the Web, sites that offer a Markdown version of their pages, and your own files. A site that only has HTML shows a page saying so.
.md file or a folder onto Dowwwn..md file to Dowwwn from the Files app.A file in iCloud Drive that says Dowwwn can't read this file: open it once more with Open File…, and Dowwwn remembers it from then on.
Formulas are written in LaTeX, between dollars: $…$ in the line, $$…$$ on a line of their own. Drawings are ```svg blocks. The maths and SVG pages show what works.
macOS 27, iOS 27 or iPadOS 27, or later.