Examine source code of Painted Red snow

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Red snow",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(44, 13, 15, 0.26)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(249, 253, 255)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(161, 80, 94)",
      "toolbar_field_text": "rgb(248, 13, 36)",
      "tab_line": "rgba(249, 253, 255, 0.8)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(174, 0, 0)",
      "button_background_active": "rgb(233, 223, 195)",
      "sidebar_highlight_text": "rgb(116, 213, 255)",
      "tab_selected": "rgba(101, 5, 21, 0.3)",
      "tab_text": "rgb(255, 252, 252)",
      "toolbar_field_border_focus": "rgba(238, 174, 174, 0)",
      "toolbar_field_focus": "rgb(199, 234, 255)",
      "toolbar_field_text_focus": "rgb(172, 9, 9)",
      "tab_loading": "rgba(249, 253, 255, 0.8)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e3f194d7-41c7-40ef-9e82-8322f5254f8d}"
    }
  }
}