Examine source code of krunker

{
  "name": "krunker",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Desert.jpg"
    },
    "colors": {
      "frame": "rgba(73, 114, 209, 1)",
      "tab_background_text": "rgba(0, 0, 0, 1)",
      "toolbar": "rgba(214, 40, 40, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1ea1741d-d8da-49ed-ad18-a5ad6ef43533}"
    }
  }
}