A single-file markdown reader with the reading-mode controls iOS keeps to itself.
Double-click a .md file and get a properly typeset page, then tune it until it's comfortable.
Get it
Download ReadingDesk.exe below and double-click it. A small setup window opens: pick a folder, press Install. That one file is the whole app, about 60 KB. It installs a copy of itself, unpacks the reader beside it, draws its icon, adds a Start Menu entry, and registers as a handler for .md. Nothing is written outside your own user account, and no admin rights are needed.
It is unsigned, so SmartScreen will ask first. Choose More info, then Run anyway.
One step is yours. Windows 11 protects the default-app choice with a hash, so no installer can set it for you. Right-click any .md file, choose Open with, then Choose another app, pick Markdown Reading Desk, and tick Always use this app.
To remove it later, run the setup window again and press Uninstall. The previous .md app is put back.
What's in it
Page tint. Auto, Paper, Sepia, Solar, Night, Slate, Dusk, and a high-contrast Ink.
Typeface. Literata, Fraunces, IBM Plex Sans, Atkinson Hyperlegible (designed for low vision), IBM Plex Mono, or your system sans.
Measure and rhythm. Sliders, not presets: text size, line height, column width, paragraph gap, letter spacing, word spacing.
Reading aids. Bionic emphasis with adjustable strength, focus dimming, a cursor-following reading ruler, justification, hyphenation, and a drop cap.
Along the way. A contents sidebar built from the headings, a progress line, live word count and reading time, read-aloud, print, save-as-styled-HTML, and a source pane that renders as you type. Your settings are remembered in the browser.
Notes
reading-desk.html in the source also works on its own. Open it in any browser and drop a .md file on the window.
Markdown is parsed by marked and sanitized with DOMPurify, both from cdnjs; fonts come from Google Fonts. Those are the only network requests. Offline, the page falls back to system fonts and shows the plain text.
Requires .NET Framework 4.x, which ships with Windows. Building from source needs nothing else.