Examine source code of Breeze Duo for KDE Plasma

{
  "manifest_version": 2,
  "name": "Breeze Duo",
  "description": "Web Extension to improve Firefox look in KDE With Breeze theme",
  "version": "1.5",
  "icons": {
    "150": "kde-128x128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "theme"
  ]
}