CSS Override Extension

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 3,
  "name": "CSS Override Extension",
  "version": "1.0",
  "description": "Override web page CSS with custom styles.",
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "action": {
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "images/icon48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "popup.html",
        "popup.js",
        "styles.css"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ]
}