Examine source code of mottled concrete1

{
  "theme": {
    "images": {
      "theme_frame": "concrete-bg-4.jpg"
    },
    "colors": {
      "frame": "#706c6c",
      "tab_background_text": "#f5eded"
    }
  },
  "version": "2.0",
  "name": "mottled concrete1",
  "manifest_version": 2,
  "description": "simple mottled concrete"
}