Examine source code of Green Theme by manolo

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Green Theme",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right bottom"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(43, 44, 44, 0.6)",
      "toolbar_text": "rgba(232, 232, 235, 0.87)",
      "frame": "rgb(72, 74, 75)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgba(76, 76, 79, 0.38)",
      "toolbar_field_text": "rgba(232, 232, 235, 0.91)",
      "tab_line": "rgba(52, 52, 54, 0.71)",
      "popup": "rgba(36, 36, 37, 0.52)",
      "popup_text": "rgb(232, 232, 235)",
      "tab_loading": "rgba(52, 52, 54, 0.71)"
    }
  }
}