Examine source code of Subtle Firefox

{
  "theme": {
    "images": {
      "theme_frame": "Subtle_Header.jpg"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#000"
    }
  },
  "version": "2.0",
  "name": "Subtle Firefox",
  "manifest_version": 2,
  "description": "My first shot on a firefox theme.\n\nThis is based of the Standard firefox theme.\n\nI watched many of the themes out there and got really inspired to make one of my own. I wanted to make a very subtle firefox theme that was clean and would not steal too much attention. \n\nIm hoping people will enjoy it"
}