Examine source code of BetterMint Chess

{
  "manifest_version": 3,
  "name": "BetterMint - v1.9.7",
  "short_name": "BetterMint v1.9.7",
  "icons": {
    "16": "img/logo-16.png",
    "48": "img/logo-48.png",
    "128": "img/logo-128.png"
  },
  "version": "1.9.7",
  "description": "BetterMint is a tool that helps you get better at chess.",
  "permissions": [
    "storage",
    "declarativeNetRequest"
  ],
  "host_permissions": [
    "http://*.chess.com/*",
    "https://*.chess.com/*"
  ],
  "content_scripts": [
    {
      "js": [
        "js/loader.js"
      ],
      "css": [
        "css/depthbar.css",
        "css/evalbar.css",
        "css/material-icon.css"
      ],
      "matches": [
        "https://*.chess.com/*"
      ],
      "run_at": "document_start"
    }
  ],
  "declarative_net_request": {
    "rule_resources": [
      {
        "id": "ruleset_1",
        "enabled": true,
        "path": "rules.json"
      }
    ]
  },
  "action": {
    "default_popup": "html/options.html"
  },
  "web_accessible_resources": [
    {
      "resources": [
        "js/bettermint.js",
        "html/options.html"
      ],
      "matches": [
        "https://*.chess.com/*"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "bettermint@basicsellout.tk",
      "strict_min_version": "42.0"
    }
  }
}