Examine source code of 4ETB - 4 EYES TOOLBOX

{
  "manifest_version": 2,
  "name": "4ETB",
  "version": "2.2.0",
  "description": "4ETB - 4 EYES TOOLBOX.",
  "author": "fiioonnn",
  "homepage_url": "https://github.com/fiioonnn/4ETB/",
  "icons": {
    "48": "assets/icons/48.png",
    "96": "assets/icons/96.png"
  },
  "browser_action": {
    "default_icon": "assets/icons/48.png",
    "default_title": "4ETB - 4 EYES TOOLBOX",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false,
    "type": "module"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content/content.js",
        "content/notify.js",
        "content/utils.js"
      ]
    },
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "assets/css/notify.css",
        "assets/css/mark.css"
      ]
    }
  ],
  "permissions": [
    "activeTab",
    "<all_urls>"
  ],
  "web_accessible_resources": [
    "assets/icons/4ETB.svg",
    "assets/icons/chevron-left.svg",
    "assets/icons/chevron-right.svg",
    "assets/fonts/montserrat-v25-latin-500.eot",
    "assets/fonts/montserrat-v25-latin-500.svg",
    "assets/fonts/montserrat-v25-latin-500.ttf",
    "assets/fonts/montserrat-v25-latin-500.woff",
    "assets/fonts/montserrat-v25-latin-500.woff2",
    "assets/fonts/montserrat-v25-latin-600.eot",
    "assets/fonts/montserrat-v25-latin-600.svg",
    "assets/fonts/montserrat-v25-latin-600.ttf",
    "assets/fonts/montserrat-v25-latin-600.woff",
    "assets/fonts/montserrat-v25-latin-600.woff2",
    "assets/fonts/montserrat-v25-latin-700.eot",
    "assets/fonts/montserrat-v25-latin-700.svg",
    "assets/fonts/montserrat-v25-latin-700.ttf",
    "assets/fonts/montserrat-v25-latin-700.woff",
    "assets/fonts/montserrat-v25-latin-700.woff2",
    "assets/fonts/montserrat-v25-latin-800.eot",
    "assets/fonts/montserrat-v25-latin-800.svg",
    "assets/fonts/montserrat-v25-latin-800.ttf",
    "assets/fonts/montserrat-v25-latin-800.woff",
    "assets/fonts/montserrat-v25-latin-800.woff2"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{f368d7fc-42fc-4b35-a061-5c289ebc90e6}"
    }
  }
}