Examine source code of Night Firefox

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#141212",
      "tab_background_text": "#cf5555"
    }
  },
  "version": "2.0",
  "name": "Night Firefox",
  "manifest_version": 2,
  "description": "This is the Night Firefox theme, I got this idea from the \"Beta, Nightly, Developer Edition\" page, and what came out of it was this. I hope you like it, don't judge it, I have just downloaded it last night, I am new to Firefox."
}