Examine source code of hot&cold3

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "ffthm3",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg",
        "images/1.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center",
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat",
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(0, 0, 0)",
      "toolbar_text": "rgb(242, 215, 44)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(84, 199, 27)",
      "toolbar_field": "rgb(218, 7, 7)",
      "toolbar_field_text": "rgb(191, 236, 51)",
      "tab_line": "rgb(235, 240, 39)",
      "popup": "rgba(0, 0, 0, 0.83)",
      "popup_text": "rgb(255, 0, 0)",
      "tab_loading": "rgb(235, 240, 39)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{dde5e221-8339-4554-bc61-e03d5eb4e03d}"
    }
  }
}