Examine source code of angsbild

{
  "theme": {
    "images": {
      "theme_frame": "firefoxupptill.jpg"
    },
    "colors": {
      "frame": "#8aa11a",
      "tab_background_text": "#0b2b06"
    }
  },
  "version": "2.0",
  "name": "angsbild",
  "manifest_version": 2,
  "description": "green grass"
}