Examine source code of Simplicity look

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Simple Useful",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(0, 0, 0)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(17, 38, 51)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgba(38, 38, 43, 0.83)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(241, 252, 4)",
      "popup": "rgb(0, 0, 0)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_hover": "rgb(51, 106, 212)",
      "icons": "rgb(255, 255, 255)",
      "tab_loading": "rgb(241, 252, 4)"
    }
  }
}