Examine source code of Dark Grey

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Grey Light",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgba(72, 71, 77, 0.87)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(49, 48, 56)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(50, 49, 58)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(66, 66, 66)",
      "popup": "rgb(49, 48, 56)",
      "popup_text": "rgb(255, 255, 255)",
      "popup_highlight_text": "rgb(255, 255, 255)",
      "sidebar_border": "rgb(255, 255, 255)",
      "tab_loading": "rgb(66, 66, 66)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5621e7bb-12e0-4294-93c1-f4f49667c676}"
    }
  }
}