Examine source code of concrete+light

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#000000",
      "tab_background_text": "#b8b8b8"
    }
  },
  "version": "2.0",
  "name": "concrete+light",
  "manifest_version": 2,
  "description": "Light from above falls on concrete wall.\nArt-Museum in Switzerland"
}