Examine source code of day to night

{
  "theme": {
    "images": {
      "theme_frame": "daytonight.jpg"
    },
    "colors": {
      "frame": "#5c5555",
      "tab_background_text": "#3b2020"
    }
  },
  "version": "2.0",
  "name": "day to night",
  "manifest_version": 2,
  "description": "gradation of day to night. Footer is night to day"
}