Examine source code of Indigo Night

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#f7f2f2"
    }
  },
  "version": "2.0",
  "name": "Indigo Night",
  "manifest_version": 2,
  "description": "Hi friends, this is my first theme for firefox. Please check it out and give your suggestions. Expect more soon. Comments are always welcomed so that I can improve and create more..Thank You.."
}