Examine source code of New Dark Theme

{
  "manifest_version": 2,
  "version": "0.0.0",
  "name": "New Dark Theme",
  "description": "A new and better dark theme for Firefox",
  "theme": {
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(47, 47, 47)",
      "toolbar_text": "rgb(167, 167, 167)",
      "frame": "rgb(35, 35, 35)",
      "tab_background_text": "rgb(167, 167, 167)",
      "toolbar_field": "rgb(37, 37, 37)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(169, 169, 169)",
      "popup": "rgb(47, 47, 47)",
      "popup_text": "rgb(194, 194, 194)",
      "tab_loading": "rgb(169, 169, 169)"
    }
  }
}