Examine source code of gradientfun

{
  "theme": {
    "images": {
      "theme_frame": "Persona_Header.png"
    },
    "colors": {
      "frame": "#b3b1b1",
      "tab_background_text": "#fafafa"
    }
  },
  "version": "2.0",
  "name": "gradientfun",
  "manifest_version": 2,
  "description": "Gradient image"
}