Examine source code of Yellow ff

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Yellow field",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat-x"
      ]
    },
    "colors": {
      "toolbar": "rgba(255, 255, 128, 0.8)",
      "toolbar_text": "rgb(63, 128, 0)",
      "frame": "rgb(117, 219, 0)",
      "tab_background_text": "rgb(0, 0, 0)",
      "toolbar_field": "rgb(224, 255, 190)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(136, 255, 0)",
      "popup": "rgb(35, 70, 0)",
      "popup_text": "rgb(255, 255, 191)",
      "tab_loading": "rgb(136, 255, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b76bf2e8-999e-46aa-812c-e37bdf168696}"
    }
  }
}