Examine source code of Flat grey

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#323232",
      "tab_background_text": "#d7d7d7"
    }
  },
  "version": "2.0",
  "name": "Flat grey",
  "manifest_version": 2,
  "description": "A flat darker theme"
}