Examine source code of Simple Designs 4

{
  "theme": {
    "images": {
      "theme_frame": "Design4-Header.jpg"
    },
    "colors": {
      "frame": "#4d4d4d",
      "tab_background_text": "#f5b70c"
    }
  },
  "version": "2.0",
  "name": "Simple Designs 4",
  "manifest_version": 2,
  "description": "Simple design. Add some aesthetic quality to your browser without clutter.\nDesigned to work with tabs on top."
}