Examine source code of SapphireX

{
  "manifest_version": 2,
  "name": "SapphireX",
  "description": "A lil Sapphire can surely enhance this Emerald",
  "version": "0.0.7",
  "icons": {
    "64": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "sapphirex@sa.xe",
      "strict_min_version": "48.0"
    }
  },
  "background": {
    "scripts": [
      "core.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.emeraldchat.com/app"
      ],
      "js": [
        "./src/dashboard.js"
      ],
      "css": [
        "./src/style.css"
      ]
    }
  ]
}