Examine source code of afore

{
  "manifest_version": 2,
  "name": "afore",
  "author": "khristopher pienda",
  "version": "1.0",
  "description": "in this extension, you can add the styles then you want to and that styles will be shown on every site was open on this browser",
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "css": [
        "main.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9f039146-1f4f-4138-858a-2b9c3e68f8dd}"
    }
  }
}