Examine source code of Cool turtle theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Cool turtle theme",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(33, 75, 22, 0.5)",
      "toolbar_text": "rgb(123, 255, 211)",
      "frame": "rgb(22, 54, 75)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgba(0, 0, 0, 0.2)",
      "toolbar_field_text": "rgb(123, 255, 211)",
      "tab_line": "rgb(28, 171, 176)",
      "popup": "rgba(22, 75, 50, 0.69)",
      "popup_text": "rgb(123, 255, 211)",
      "tab_loading": "rgb(28, 171, 176)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d10436ee-45cf-42d6-92aa-d76e5d7b95b0}"
    }
  }
}