Examine source code of Themecool

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Hugolin-theme",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-037-b73f9b34467ba541de861f5b4c0c6316.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(231, 238, 242)",
      "toolbar_text": "rgba(185, 34, 4, 0.98)",
      "frame": "rgb(78, 208, 250)",
      "tab_background_text": "rgb(0, 0, 0)",
      "toolbar_field": "rgb(246, 232, 243)",
      "toolbar_field_text": "rgb(48, 0, 255)",
      "tab_line": "rgb(5, 242, 209)",
      "popup": "rgb(244, 229, 212)",
      "popup_text": "rgb(133, 10, 47)",
      "tab_loading": "rgb(5, 242, 209)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{248581dd-b809-444a-8c78-97af0065f404}"
    }
  }
}