Examine source code of Soft Gradient

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#1bf295",
      "tab_background_text": "#181b66"
    }
  },
  "version": "2.0",
  "name": "Soft Gradient",
  "manifest_version": 2,
  "description": "Soft gradient for Quantum Firefox, light and cool."
}