Examine source code of Paper Theme

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#636e73",
      "tab_background_text": "#c8ccce"
    }
  },
  "version": "2.0",
  "name": "Paper Theme",
  "manifest_version": 2,
  "description": "Same shade of blue as paper for gnome"
}