Examine source code of Just arrow

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Just arrow",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(123, 123, 123, 0.25)",
      "toolbar_text": "rgb(42, 42, 42)",
      "frame": "rgb(255, 255, 255)",
      "tab_background_text": "rgb(96, 96, 96)",
      "toolbar_field": "rgba(133, 133, 133, 0.75)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(0, 0, 0)",
      "popup": "rgba(123, 123, 123, 0.75)",
      "popup_text": "rgb(0, 0, 0)",
      "tab_loading": "rgb(0, 0, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f14aa7ec-a36d-4ae8-9a08-0a69bdde4583}"
    }
  }
}