Examine source code of Sunset Sky Gradient

{
  "manifest_version": 2,
  "version": "1.1",
  "name": "Sunset Sky Gradient",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(58, 89, 105, 0.17)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(47, 101, 147)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(47, 101, 147)",
      "tab_line": "rgba(47, 101, 147, 0.5)",
      "popup": "rgba(63, 68, 72, 0.8)",
      "popup_text": "rgb(222, 222, 222)",
      "tab_loading": "rgba(47, 101, 147, 0.5)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{da20880b-06a6-4556-ae44-cc71dc4aaa4d}"
    }
  }
}