Chrome Extension That Adds Dark Mode to Any Website

Force dark mode on every website. Toggle per-site, automatic contrast adjustments, images preserved.

utilitiesintermediate#dark-mode#accessibility#css
PlugThis prompt
Build a Chrome extension called "Dark Mode Everywhere" that applies dark mode to any website. The extension should: (1) inject CSS into every webpage that inverts background colors to dark and adjusts text contrast, (2) preserve images, videos, and SVGs (don't invert them), (3) provide a popup with a per-site toggle (on/off for the current domain) and a master toggle, (4) save per-site preferences in chrome.storage.local, (5) include a few style modes: "Smart Invert" (CSS filter-based), "Dim" (overlay-based), "Custom" (user picks colors). Permissions: storage, activeTab. Host permissions: <all_urls>. Manifest V3 with content script and content CSS.

What this extension does

Applies dark mode to any website that doesn't have one. Three modes: Smart Invert (CSS filter), Dim (overlay), or Custom (user-picked colors). Per-site on/off toggle remembers preferences.

How it works

A content script injects CSS at document_start that overrides backgrounds and adjusts text colors. Images and videos are excluded from inversion. The popup uses chrome.tabs to detect the current domain and toggle CSS injection per site.

Permissions used: storage, activeTab

Host permissions: <all_urls>

Who builds this

For users who prefer dark UIs and find sites without native dark mode harsh on the eyes — especially at night. Works on legacy sites, government portals, internal tools, and anywhere dark mode hasn't been added.

How to build it in 3 minutes

  1. Sign in to PlugThis and open the chat input.
  2. Copy the prompt above and paste it into the chat.
  3. PlugThis generates the full Manifest V3 extension in 60-90 seconds.
  4. Download the zip, extract it, and load it via chrome://extensions developer mode.

Build it now, free.

Paste the prompt above into PlugThis and ship your extension in 3 minutes.