Examine source code of Thundercats_TB4

{
  "theme": {
    "images": {
      "theme_frame": "Thundercats_TB_Header.JPG"
    },
    "colors": {
      "frame": "#d44e4e",
      "tab_background_text": "#ab4141"
    }
  },
  "version": "2.0",
  "name": "Thundercats_TB4",
  "manifest_version": 2,
  "description": "Inspired by Original Thundercats design made by Apokalyps (found here in Personas site).  This version was edited to fit Thunderbird 4.0b"
}