Examine source code of firefloss (no image)

{
  "manifest_version": 2,
  "version": "3.1",
  "name": "firefloss-no-image",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(100, 94, 130)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(58, 54, 75)",
      "tab_background_text": "rgb(255, 184, 209)",
      "toolbar_field": "rgb(128, 119, 168)",
      "toolbar_field_text": "rgb(255, 184, 209)",
      "tab_line": "rgba(255, 243, 0, 0)",
      "popup": "rgb(58, 54, 75)",
      "popup_text": "rgb(255, 184, 209)",
      "toolbar_bottom_separator": "rgb(58, 54, 75)",
      "tab_loading": "rgba(255, 243, 0, 0)"
    }
  }
}