Examine source code of fish background

{
  "name": "fishbackground",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "fishbackground.png"
    },
    "colors": {
      "frame": "rgba(218, 197, 142, 1)",
      "tab_background_text": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{cab6e556-cc23-4925-9d2a-3e9f3a854e7c}"
    }
  }
}