Examine source code of no4theme

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#f9f9fb",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "no4theme",
  "manifest_version": 2,
  "description": "simple clean and slick no.4 theme"
}