Examine source code of Behind the Horizon

{
  "name": "Behind the Horizon",
  "manifest_version": 2,
  "version": "4.0",
  "theme": {
    "images": {
      "theme_frame": "abstrakt139.png"
    },
    "colors": {
      "frame": "rgba(64, 172, 255, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(2, 163, 199, 0.24)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(163, 190, 207, 1)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(76, 255, 237, 0.52)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1c0fdf6f-369e-4faa-add4-44f4832f87db}"
    }
  }
}