Examine source code of YURI-Lily-

{
  "theme": {
    "images": {
      "theme_frame": "FFOX_A01.jpg"
    },
    "colors": {
      "frame": "#c5c6c7",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "YURI-Lily-",
  "manifest_version": 2,
  "description": "It is an original illustration."
}