Examine source code of Leetcode-Difficulty-Hide

{
  "description": "Hides the difficulty on leetcode problems. Makes the text color and background black and increases the width so it doesn't depend on the text. Repeats for a few seconds as Leetcode loads asynchronously.",
  "manifest_version": 2,
  "name": "Leetcode-Difficulty-Hide",
  "version": "0.2",
  "homepage_url": "https://github.com/c-git/leetcode_extension",
  "browser_specific_settings": {
    "gecko": {
      "id": "onebgz1@gmail.com"
    }
  },
  "icons": {
    "48": "icons/see-no-evil-monkey.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "https://leetcode.com/problems/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ]
}