Examine source code of Theme 45

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#c7ebca",
      "tab_background_text": "#000"
    }
  },
  "version": "2.0",
  "name": "Theme 45",
  "manifest_version": 2,
  "description": "For testers of webapplications. directly see your browser when this theme is applied"
}