Examine source code of Rainbow Swoosh

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#000000",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Rainbow Swoosh",
  "manifest_version": 2,
  "description": "Source image: <a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/4deb642e3b2c42bed7debe9e2475714950387b18d08a3215aabb7418fc2cc6c2/https%3A//pixabay.com/en/abstract-line-wave-design-pattern-140898/\">https://pixabay.com/en/abstract-line-wave-design-pattern-140898/</a>"
}