Examine source code of Colour Contrast Checker

{
  "manifest_version": 3,
  "name": "Colour Contrast Checker",
  "short_name": "CC Checker",
  "description": "Check the contrast between different colour combinations against WCAG standards",
  "version": "1.4.2",
  "action": {
    "default_title": "Open CC Checker"
  },
  "icons": {
    "16": "./favicons/favicon-16x16.png",
    "48": "./favicons/favicon-48x48.png",
    "128": "./favicons/favicon-128x128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{43c561d7-7b39-4ce7-978d-bd250dd6680c}",
      "strict_min_version": "109.0"
    }
  },
  "permissions": [
    "activeTab"
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "index.html",
        "fonts/avenir-next-variable.woff2"
      ],
      "matches": [
        "<all_urls>"
      ],
      "use_dynamic_url": true
    }
  ],
  "background": {
    "scripts": [
      "./app/background.js"
    ],
    "page": "index.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "./app/content.js"
      ]
    }
  ]
}