Examine source code of Forest shadow

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Forest shadow",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left center"
      ],
      "additional_backgrounds_tiling": [
        "repeat-x"
      ]
    },
    "colors": {
      "toolbar": "rgba(34, 41, 44, 0.85)",
      "toolbar_text": "rgb(248, 248, 248)",
      "frame": "rgb(34, 41, 44)",
      "tab_background_text": "rgb(245, 245, 245)",
      "toolbar_field": "rgb(23, 25, 20)",
      "toolbar_field_text": "rgb(248, 248, 248)",
      "tab_line": "rgb(61, 156, 15)",
      "popup": "rgb(34, 41, 44)",
      "popup_text": "rgb(255, 255, 255)",
      "tab_loading": "rgb(61, 156, 15)"
    }
  }
}