Examine source code of CSS Filters Editor

{
  "name": "CSS Filters Editor",
  "short_name": "Filters",
  "version": "1.0.0",
  "manifest_version": 2,
  "devtools_page": "devtools.html",
  "applications": {
    "gecko": {
      "id": "@FiltersEdit",
      "strict_min_version": "54.0"
    }
  },
  "permissions": [
    "tabs",
    "activeTab",
    "<all_urls>"
  ]
}