Examine source code of invert snow

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "invert snow",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(30, 31, 31)",
      "toolbar_text": "rgb(233, 233, 233)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(204, 204, 204)",
      "toolbar_field": "rgb(24, 24, 24)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(59, 91, 87)",
      "popup": "rgb(27, 40, 45)",
      "popup_text": "rgb(140, 140, 140)",
      "tab_loading": "rgb(59, 91, 87)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{afc49835-a6c7-4879-8855-b3cae34f69fd}"
    }
  }
}