Examine source code of monochrome grey theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "grey theme",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-006-51ab495c5f5dde6a3cddb22484acd00d.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(170, 170, 170)",
      "toolbar_text": "rgb(56, 56, 56)",
      "frame": "rgb(83, 83, 83)",
      "tab_background_text": "rgb(224, 224, 224)",
      "toolbar_field": "rgb(224, 224, 224)",
      "toolbar_field_text": "rgb(56, 56, 56)",
      "tab_line": "rgb(56, 56, 56)",
      "popup": "rgb(56, 56, 56)",
      "popup_text": "rgb(224, 224, 224)",
      "tab_loading": "rgb(56, 56, 56)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c2f2fdb3-8b44-4f4d-9ae9-501cd553a86e}"
    }
  }
}