Examine source code of ultimate-dark-theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "ultimate",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(49, 67, 82)",
      "toolbar_text": "rgb(250, 250, 250)",
      "frame": "rgb(27, 40, 45)",
      "tab_background_text": "rgb(219, 222, 224)",
      "toolbar_field": "rgb(102, 115, 127)",
      "toolbar_field_text": "rgb(250, 250, 250)",
      "tab_line": "rgb(241, 106, 84)",
      "popup": "rgb(27, 40, 45)",
      "popup_text": "rgb(219, 222, 224)",
      "button_background_active": "rgb(87, 59, 178)",
      "button_background_hover": "rgb(114, 82, 207)",
      "icons_attention": "rgb(95, 224, 198)",
      "tab_loading": "rgb(241, 106, 84)"
    }
  }
}