Examine source code of gradientglow-dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "gradient-dark",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png",
        "images/1.png",
        "images/2.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center top",
        "right top",
        "right center"
      ],
      "additional_backgrounds_tiling": [
        "repeat",
        "repeat",
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(71, 71, 71, 0.35)",
      "toolbar_text": "rgba(255, 255, 255, 0.82)",
      "frame": "rgb(44, 20, 63)",
      "tab_background_text": "rgb(220, 214, 228)",
      "toolbar_field": "rgba(255, 255, 255, 0.59)",
      "toolbar_field_text": "rgb(41, 0, 41)",
      "tab_line": "rgba(154, 109, 203, 0.54)",
      "popup": "rgb(187, 175, 200)",
      "popup_text": "rgb(0, 0, 0)",
      "tab_loading": "rgba(154, 109, 203, 0.54)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e7fe1c1f-8f83-45d7-b540-bd7299ab957d}"
    }
  }
}