Examine source code of Horologium

{
  "manifest_version": 2,
  "version": "1.3",
  "name": "Horologium",
  "developer": {
    "name": "Stanislav Panin"
  },
  "icons": {
    "16": "icons/horologium-cyan.svg",
    "48": "icons/horologium-cyan.svg",
    "128": "icons/horologium-cyan.svg"
  },
  "description": "Manage time you spend on websites to enhance productivity.",
  "permissions": [
    "alarms",
    "storage",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "browser_action": {
    "theme_icons": [
      {
        "dark": "icons/horologium.svg",
        "light": "icons/horologium-light.svg",
        "size": 32
      },
      {
        "dark": "icons/horologium.svg",
        "light": "icons/horologium-light.svg",
        "size": 48
      }
    ],
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{53edae12-fe48-4c23-9070-a959c844585b}"
    }
  }
}