Examine source code of doom world

{
  "name": "doom world",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "doom world (3) (2).png"
    },
    "colors": {
      "frame": "rgba(0, 0, 0, 1)",
      "tab_background_text": "rgba(255, 218, 186, 1)",
      "toolbar": "rgba(48, 24, 0, 0.74)",
      "bookmark_text": "rgba(219, 110, 0, 1)",
      "toolbar_field": "rgba(3, 3, 3, 0.63)",
      "toolbar_field_text": "rgba(255, 121, 3, 1)",
      "tab_line": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7441bea9-8ba6-4d8b-8eeb-c00e90ca07c9}"
    }
  }
}