DarkMode — darkener for the resistant cases

A browser extension that does nothing until asked. On sites that shrug off ordinary dark-mode extensions (inline styles, canvases, color-scheme: light lock-in — e.g. foxglove.dev), click the toolbar icon and the page goes dark via CSS filter inversion, which flips what polite per-element theming can't reach. Optionally remember a site so it auto-darkens on future visits.

Behavior contract

• Inert by default. No site is touched until the user asks. Installed and enabled ≠ anything happens.
• Ask = click the toolbar icon → "Darken this page" (one-shot, this tab). The popup shows the live state; the button toggles back.
• Remember = check "Always dark on <host>" in the popup. The host is stored in storage.sync; future visits auto-darken at document_start (no light flash). Uncheck to forget. Nothing is ever auto-added — only the user includes sites.
• Per-visit toggles never persist. Reload a non-remembered page → light again.

Engine

Color-wheel inversion (html.cr-dark { filter: invert(1) }): white→black, black→white, every hue → its complement (red↔cyan, yellow↔blue) — the flip that reaches inline styles, canvases and color-scheme: light lock-ins that polite per-element theming can't. Pictures are exempt: img / picture / video / canvas / iframe / embed / object / svg image are inverted back to natural colors. No hue-rotate, no forced root background (user spec 2026-09-04 — a forced background under the filter would invert into a light wash). Gated entirely on an <html> class the content script adds — the rules are inert without it.

Known trade-offs of the filter tactic (accepted for the resistant case):

• position: fixed headers can misbehave (a filter on the root makes them behave like their containing block) — cosmetic on most pages.
• Canvas/webgl apps (e.g. embedded Studio) are inverted as a whole; hues land on complements, which is the requested wheel-flip behavior for a light app.
• Screenshots/screen-share of the page will capture the dark rendering.

Install (daily Chromium — permanent)

chromium://extensions → Developer mode → Load unpacked → this repo dir (manifest.json at root). Persists across restarts. Zen/Firefox: about:debugging#/runtime/this-firefox → Load Temporary Add-on → manifest.json.

Dev notes

• Node for syntax checks: /c/Users/Mike2/AppData/Local/hermes/node/node.exe (node --check content.js popup.js background.js).
• On every edit bump BOTH manifest.json "version" and the in-script VERSION constants so about:debugging / the popup show an honest build.
• Test target #1: foxglove.dev (resists the stock Dark Mode extension). Load unpacked, click the icon on a foxglove.dev page, then tick "Always dark".