Examine source code of Enforce Browser Fonts

{
  "manifest_version": 2,
  "name": "Enforce Browser Fonts",
  "version": "1.2",
  "description": "Enforce browser fonts easily on websites instead of letting them use their own fonts",
  "homepage_url": "https://github.com/jayesh-bhoot/enforce-browser-fonts",
  "browser_specific_settings": {
    "gecko": {
      "id": "{83e08b00-32de-44e7-97bb-1bab84d1350f}"
    }
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/off.svg",
      "96": "icons/off.svg"
    }
  },
  "background": {
    "scripts": [
      "js/core.js"
    ]
  },
  "options_ui": {
    "page": "preferences.html",
    "browser_style": true
  },
  "icons": {
    "48": "icons/on.svg",
    "96": "icons/on.svg"
  },
  "commands": {
    "_execute_browser_action": {
      "description": "Shortcut to toggle the enforcement of browser fonts",
      "suggested_key": {
        "default": "Alt+Comma"
      }
    }
  },
  "permissions": [
    "browserSettings",
    "tabs",
    "storage"
  ]
}