Examine source code of Clean Dark (Black)

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#2d2d2d",
      "tab_background_text": "#eeeeee"
    }
  },
  "version": "2.0",
  "name": "Clean Dark (Black)",
  "manifest_version": 2,
  "description": "A simple, clean, dark theme, for people who just like to see the icons in their browser ."
}