Examine source code of A Day in Space

{
  "name": "A Day in Space",
  "manifest_version": 2,
  "version": "4.0",
  "theme": {
    "images": {
      "theme_frame": "space-1.png"
    },
    "colors": {
      "frame": "rgba(229, 230, 232, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(13, 98, 117, 0.25)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(22, 62, 71, 0.68)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)",
      "tab_line": "rgba(136, 143, 37, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4264a1de-6bbb-4e1f-926f-54d9232d053d}"
    }
  }
}