Examine source code of VertiFix

{
  "manifest_version": 2,
  "name": "VertiFix",
  "version": "1.0.6",
  "description": "Fixes display issues for GitHub.com, especially on vertical or smaller viewports. Billboard icons created by Roundicons - Flaticon",
  "homepage_url": "https://github.com/philecker/github-vertifix",
  "icons": {
    "24": "icons/VertiFix_24x24.png",
    "48": "icons/VertiFix_48x48.png",
    "128": "icons/VertiFix_128x128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.github.com/",
        "*://github.com/dashboard"
      ],
      "js": [
        "vertifix.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{6d3906f3-f8fe-48ce-be42-f4418d249cf6}"
    }
  }
}