Examine source code of Themes for Teams

{
  "manifest_version": 3,
  "name": "Themes for Teams",
  "version": "0.4.1",
  "description": "Custom Styles for Microsoft Teams to boost productivity.",
  "permissions": [
    "storage"
  ],
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://teams.microsoft.com/v2/*"
      ],
      "css": [
        "styles.css"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "styles.css",
        "no-animations.css",
        "themes/*.css"
      ],
      "matches": [
        "*://teams.microsoft.com/*"
      ]
    }
  ],
  "action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "themes-for-teams@goshow.me"
    }
  }
}