Examine source code of Gradient01

{
  "theme": {
    "images": {
      "theme_frame": "gradient01.jpg"
    },
    "colors": {
      "frame": "#2f415b",
      "tab_background_text": "#222222"
    }
  },
  "version": "2.0",
  "name": "Gradient01",
  "manifest_version": 2,
  "description": "A simple and plain gradient."
}