Examine source code of Layered Highlights

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#330080",
      "tab_background_text": "#ccccff"
    }
  },
  "version": "2.0",
  "name": "Layered Highlights",
  "manifest_version": 2,
  "description": "A simplistic and eye-catching Firefox theme with a purple background and warm highlights."
}