Examine source code of Font Inspector & CSS Picker

{
  "manifest_version": 2,
  "name": "Font Inspector & CSS Picker",
  "version": "1.0.0",
  "description": "Identify any font on any website. Click to inspect text and instantly see font-family, weight, size, color and CSS. Copy with one click.",
  "author": "HTML.Design",
  "homepage_url": "https://html.design",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "font-inspector@html.design",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": {
      "48": "icons/icon-48.png"
    },
    "default_title": "Font Inspector & CSS Picker",
    "default_popup": "popup/popup.html"
  }
}