Examine source code of Forever Friends...

{
  "theme": {
    "images": {
      "theme_frame": "ForeverFriends_header_byLisa.jpg"
    },
    "colors": {
      "frame": "#e7e8d0",
      "tab_background_text": "#666600"
    }
  },
  "version": "2.0",
  "name": "Forever Friends...",
  "manifest_version": 2,
  "description": "background design, sponge dots and splashes of green, red, melon and cream with special hearts decorate your Firefox browser, BFF\n\nchild friendly persona\n\nPersonas by LisaAtTheBeach"
}