Examine source code of Olson!

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Olson!",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right bottom"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(75, 36, 5)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(11, 10, 10)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(64, 43, 9)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(201, 84, 25)",
      "popup": "rgb(202, 108, 32)",
      "popup_text": "rgb(255, 255, 255)",
      "sidebar_border": "rgb(16, 16, 19)",
      "sidebar_highlight": "rgb(202, 195, 191)",
      "sidebar_text": "rgb(255, 255, 255)",
      "sidebar": "rgb(160, 63, 14)",
      "tab_loading": "rgb(201, 84, 25)"
    }
  }
}