Examine source code of Thunder black theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Thunder",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right center"
      ],
      "additional_backgrounds_tiling": [
        "repeat-y"
      ]
    },
    "colors": {
      "toolbar": "rgba(61, 61, 241, 0)",
      "toolbar_text": "rgb(94, 94, 94)",
      "frame": "rgb(14, 14, 14)",
      "tab_background_text": "rgb(94, 94, 94)",
      "toolbar_field": "rgb(19, 19, 19)",
      "toolbar_field_text": "rgb(94, 94, 94)",
      "tab_line": "rgb(255, 255, 255)",
      "popup": "rgb(14, 14, 14)",
      "popup_text": "rgb(94, 94, 94)",
      "tab_loading": "rgb(255, 255, 255)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a3463760-49cb-4e04-b2fc-414b70a438cc}"
    }
  }
}