Examine source code of Focals_winter_theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Winter",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg",
        "images/1.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center",
        "left top"
      ],
      "additional_backgrounds_tiling": [
        "repeat",
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(162, 228, 228)",
      "toolbar_text": "rgb(13, 4, 8)",
      "frame": "rgb(20, 17, 224)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(102, 248, 248)",
      "toolbar_field_text": "rgb(5, 0, 5)",
      "tab_line": "rgb(134, 11, 180)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(134, 11, 180)",
      "tab_loading": "rgb(134, 11, 180)"
    }
  }
}