Examine source code of Fireflies at Midnight

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Fireflies at Night ",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(0, 16, 39, 0.5)",
      "toolbar_text": "rgb(255, 238, 214)",
      "frame": "rgb(21, 44, 80)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgba(255, 249, 220, 0.8)",
      "toolbar_field_text": "rgb(0, 54, 132)",
      "tab_line": "rgb(255, 221, 140)",
      "popup": "rgb(18, 54, 87)",
      "popup_text": "rgb(255, 217, 176)",
      "tab_loading": "rgb(255, 221, 140)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{52e4a0f7-1c8d-4e6d-b559-6d270b550791}"
    }
  }
}