Examine source code of Color Contrast Checker

{
  "manifest_version": 3,
  "name": "__MSG_extensionName__",
  "version": "1.2",
  "description": "__MSG_extensionDescription__",
  "default_locale": "de",
  "action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "cca@barrierefrei-geprueft.de",
      "strict_min_version": "58.0"
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  }
}