Examine source code of Darkjira

{
  "manifest_version": 3,
  "name": "Darkjira",
  "version": "1.0.0",
  "description": "Dark mode theme for self-hosted Jira (Server/Data Center)",
  "homepage_url": "https://gitlab.com/zarko.susnjar/darkjira",
  "browser_specific_settings": {
    "gecko": {
      "id": "darkjira@susnjar.xyz",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "action": {
    "default_title": "Darkjira",
    "default_popup": "popup/index.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "permissions": [
    "storage",
    "scripting",
    "activeTab"
  ],
  "optional_host_permissions": [
    "http://*/*",
    "https://*/*"
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "theme/darkjira.css"
      ],
      "matches": [
        "http://*/*",
        "https://*/*"
      ]
    }
  ]
}