Examine source code of a11y.css accessibility checker

{
  "manifest_version": 3,
  "name": "a11y.css",
  "description": "a11y.css provides warnings about possible risks and mistakes that exist in HTML code through a style sheet. This extension also provides several accessibility-related utilities.",
  "version": "2.1.0",
  "default_locale": "en",
  "browser_specific_settings": {
    "gecko": {
      "id": "a11y.css@ffoodd",
      "strict_min_version": "109.0"
    }
  },
  "permissions": [
    "activeTab",
    "storage",
    "scripting",
    "tabs"
  ],
  "action": {
    "default_title": "a11y.css",
    "default_popup": "popup/index.html",
    "default_icon": {
      "19": "icons/a11y-css_19.png",
      "38": "icons/a11y-css_38.png"
    }
  },
  "background": {
    "scripts": [
      "/scripts/background/main.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "/scripts/injected/alt.js"
      ],
      "css": [
        "/scripts/injected/alt.css"
      ],
      "run_at": "document_end"
    }
  ],
  "icons": {
    "16": "icons/a11y-css_16.png",
    "48": "icons/a11y-css_48.png",
    "128": "icons/a11y-css_128.png"
  },
  "web_accessible_resources": [
    {
      "resources": [
        "icons/info.svg",
        "icons/ko.svg",
        "icons/ok.svg",
        "scripts/injected/*",
        "css/*"
      ],
      "matches": [
        "*://*/*"
      ]
    }
  ]
}