Examine source code of Dark Walnut

{
  "name": "Dark Walnut",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "FirefoxWoodBanner.png"
    },
    "colors": {
      "frame": "rgba(229, 230, 232, 1)",
      "tab_background_text": "rgba(252, 248, 226, 0.75)",
      "toolbar": "rgba(0, 0, 0, 0.55)",
      "bookmark_text": "rgba(252, 248, 226, 0.75)",
      "toolbar_field": "rgba(252, 248, 226, 0.66)",
      "toolbar_field_text": "rgba(10, 10, 10, 0.8)",
      "tab_line": "rgba(15, 80, 50, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{093429da-0af9-4def-bb13-f42a615fc51c}"
    }
  }
}