Examine source code of GreenScreen

{
  "manifest_version": 2,
  "name": "GreenScreen",
  "version": "1.0",
  "description": "Hold the companies you shop at accountable for sustainability.",
  "icons": {
    "16": "leaf.svg",
    "32": "leaf.svg",
    "48": "leaf.svg",
    "96": "leaf.svg"
  },
  "permissions": [
    "<all_urls>",
    "tabs"
  ],
  "browser_action": {
    "default_title": "GreenScreen",
    "default_popup": "index.html",
    "browser_style": false,
    "default_icon": "leaf_no_stem.svg"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{2161d234-05e1-4d31-9e19-5059256d84df}"
    }
  }
}