Examine source code of Dark Firefox Mobile

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#353a3f",
      "tab_background_text": "#f2f2f2"
    }
  },
  "version": "2.0",
  "name": "Dark Firefox Mobile",
  "manifest_version": 2,
  "description": "A dark theme for Firefox Mobile that matches the right half of the address bar, making it appear seamless."
}