Examine source code of Lichess hide Elo

{
  "manifest_version": 2,
  "name": "Lichess hide Elo",
  "version": "2.3.6",
  "description": "Hides Elo ratings on lichess.org",
  "icons": {
    "16": "icons/icon-on.svg",
    "48": "icons/icon-on.svg",
    "96": "icons/icon-on.svg",
    "128": "icons/icon-on.svg"
  },
  "page_action": {
    "show_matches": [
      "*://lichess.org/*"
    ],
    "browser_style": true,
    "default_icon": {
      "19": "icons/icon-on.svg",
      "38": "icons/icon-on.svg"
    },
    "default_title": "Lichess hide Elo"
  },
  "content_scripts": [
    {
      "run_at": "document_start",
      "matches": [
        "*://lichess.org/*"
      ],
      "css": [
        "hideElo.css"
      ]
    },
    {
      "run_at": "document_end",
      "matches": [
        "*://lichess.org/*"
      ],
      "js": [
        "hideElo.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "lichess.hide.elo@zieren.de"
    }
  }
}