Examine source code of Soft Focus Dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Soft Focus Dark",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(21, 16, 64)",
      "toolbar_text": "rgb(112, 248, 248)",
      "frame": "rgb(180, 197, 207)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(142, 151, 214)",
      "tab_line": "rgb(97, 166, 180)",
      "popup": "rgb(216, 234, 236)",
      "popup_text": "rgb(98, 102, 183)",
      "tab_loading": "rgb(97, 166, 180)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{38461658-7506-4073-83fe-b9f4082906d6}"
    }
  }
}