Examine source code of Grey(6b6b6b)

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#6b6b6b",
      "tab_background_text": "#2b2b2b"
    }
  },
  "version": "2.0",
  "name": "Grey(6b6b6b)",
  "manifest_version": 2,
  "description": "The same grey as the window decorations on (my) Windows 8.1 machine, 6b6b6b"
}