Examine source code of Blackboard Dark Mode

{
  "description": "Overwrites color css for Hanze's Blackboard to create a dark mode.",
  "manifest_version": 2,
  "name": "blackboard-darkmode",
  "version": "0.5",
  "browser_specific_settings": {
    "gecko": {
      "id": "blackboard-dark@headtrixz"
    }
  },
  "homepage_url": "https://github.com/HeadTriXz/bb-darkmode-extension",
  "content_scripts": [
    {
      "matches": [
        "*://blackboard.hanze.nl/*",
        "*://hanze.blackboard.com/*"
      ],
      "exclude_matches": [
        "*://blackboard.hanze.nl/webapps/login/*",
        "*://hanze.blackboard.com/webapps/login/*"
      ],
      "css": [
        "dark-mode.css"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "*://blackboard.hanze.nl/webapps/login/*",
        "*://hanze.blackboard.com/webapps/login/*"
      ],
      "css": [
        "login.css"
      ],
      "run_at": "document_start"
    }
  ],
  "page_action": {
    "browser_style": true
  },
  "permissions": [
    "activeTab",
    "tabs"
  ]
}