Examine source code of Rosita :)

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Rosita :)",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-031-9570e8d1f7a5f835c92e764693337f43.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(249, 135, 221, 0.49)",
      "toolbar_text": "rgb(241, 31, 150)",
      "frame": "rgb(240, 179, 231)",
      "tab_background_text": "rgb(253, 0, 127)",
      "toolbar_field": "rgba(212, 68, 191, 0.36)",
      "toolbar_field_text": "rgb(219, 10, 98)",
      "tab_line": "rgb(177, 5, 143)",
      "popup": "rgb(244, 156, 230)",
      "popup_text": "rgb(217, 19, 172)",
      "tab_loading": "rgb(177, 5, 143)"
    }
  }
}