Examine source code of Minima Persona

{
  "theme": {
    "images": {
      "theme_frame": "topbar.png"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Minima Persona",
  "manifest_version": 2,
  "description": "Colors based on Firefox Persona design to match minimal Firefox top bar. Fit perfectly if: No bookmark toolbar with bookmark toolbar items on menu bar, small icons on navigation toolbar, and in Windows 7. Would work with additional toolbars but may not look as good."
}