Examine source code of Skulls

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "CS2 Catacombs",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(37, 39, 41, 0)",
      "toolbar_text": "rgb(229, 229, 232)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(229, 229, 232)",
      "toolbar_field": "rgb(36, 37, 37)",
      "toolbar_field_text": "rgb(229, 229, 232)",
      "tab_line": "rgb(229, 229, 232)",
      "popup": "rgb(37, 39, 41)",
      "popup_text": "rgb(229, 229, 232)",
      "tab_loading": "rgb(229, 229, 232)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4bec0693-03f8-45cc-bc8b-45bc85357eea}"
    }
  }
}