Examine source code of Jungle Animals..

{
  "name": "Jungle Animals..",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "JungleAnimalsH1Custom.jpg"
    },
    "colors": {
      "frame": "rgba(139, 245, 245, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(140, 243, 247, 0)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(140, 243, 247, 0.08)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{93b50266-b26d-4041-b04f-0f91b8d6156a}"
    }
  }
}