Examine source code of HighlandGrey

{
  "name": "HighlandGrey",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "HighlandGrey.png"
    },
    "colors": {
      "frame": "rgba(229, 230, 232, 1)",
      "tab_background_text": "rgba(66, 52, 38, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b7c9981d-9286-48c6-be29-a7a8778cfb48}"
    }
  }
}