Examine source code of Trailing Shadow

{
  "theme": {
    "images": {
      "theme_frame": "Trailing-Light-Header.jpg"
    },
    "colors": {
      "frame": "#a900b8",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Trailing Shadow",
  "manifest_version": 2,
  "description": "This is a cool picture I made in imitation of a painting."
}