Examine source code of Beauty Sunset Gradient

{
  "manifest_version": 2,
  "version": "3.0",
  "name": "Sunset",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(0, 0, 0)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(236, 219, 229)",
      "toolbar_field": "rgb(29, 0, 43)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(255, 255, 255)",
      "popup": "rgb(63, 37, 69)",
      "popup_text": "rgb(255, 255, 255)",
      "toolbar_field_border_focus": "rgba(109, 43, 116, 0)",
      "tab_loading": "rgb(255, 255, 255)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{78456686-ae37-4705-8606-ed54b3321f90}"
    }
  }
}