Examine source code of FearFox Noir

{
  "manifest_version": 2,
  "name": "FearFox Noir",
  "version": "1.3resigned1",
  "description": "Gives a dark look to your Firefox Quantum browser.",
  "icons": {
    "48": "icons/48.png",
    "96": "icons/96.png"
  },
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(85, 85, 85, 0.63)",
      "bookmark_text": "rgb(255, 255, 255)",
      "frame": "rgb(40, 40, 40)",
      "tab_background_text": "rgb(215, 215, 215)",
      "toolbar_field": "rgba(128, 128, 128, 0.29)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(215, 215, 215)",
      "popup": "rgb(40, 40, 40)",
      "popup_text": "rgb(215, 215, 215)",
      "tab_loading": "rgb(215, 215, 215)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{55d5a64a-17b1-47f3-98b8-5b254201a4e5}"
    }
  }
}