Examine source code of GitHub Floating TOC

{
  "manifest_version": 2,
  "name": "GitHub Floating TOC",
  "version": "1.0",
  "description": "Extension for GitHub to display a floating table of contents dropdown on the sidebar for READMEs.",
  "homepage_url": "https://github.com/JackyMai/github-floating-toc",
  "icons": {
    "48": "assets/icon-dark-48.png",
    "96": "assets/icon-dark-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.github.com/*"
      ],
      "js": [
        "src/contentScript.js"
      ],
      "css": [
        "src/contentScript.css"
      ]
    }
  ],
  "browser_action": {
    "default_title": "GitHub Floating TOC",
    "theme_icons": [
      {
        "light": "assets/icon-light-16.png",
        "dark": "assets/icon-dark-16.png",
        "size": 16
      },
      {
        "light": "assets/icon-light-32.png",
        "dark": "assets/icon-dark-32.png",
        "size": 32
      }
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{15d8d198-5bb4-46a3-855c-778182b1cf0b}"
    }
  }
}