Examine source code of NPC Color

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "NPC Color",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(225, 235, 239)",
      "toolbar_text": "rgb(66, 114, 164)",
      "frame": "rgb(75, 136, 151)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(47, 72, 111)",
      "tab_line": "rgb(112, 219, 248)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(98, 160, 183)",
      "tab_loading": "rgb(112, 219, 248)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{87466173-706c-43e8-bbfd-7a10d5ed0ce7}"
    }
  }
}