Examine source code of Jira dark mode

{
  "manifest_version": 2,
  "name": "Jira custom dark mode",
  "description": "This extension provided an altered light mode and additional dark mode to atlassians jira. It benefits the user experience by providing a more user-friendly design and toggleable light/dark modes.",
  "version": "1.0.2",
  "permissions": [
    "activeTab"
  ],
  "icons": {
    "16": "./icons/icon.png",
    "48": "./icons/icon.png",
    "128": "./icons/icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.atlassian.net/*"
      ],
      "js": [
        "./content/script.js"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "./content/index.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7a45d857-b303-48e1-8dfa-5e45997ac47f}"
    }
  }
}