Examine source code of High contrast gray theme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Contrast",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(191, 187, 184)",
      "toolbar_text": "rgb(66, 66, 66)",
      "frame": "rgb(51, 51, 51)",
      "tab_background_text": "rgb(181, 181, 181)",
      "toolbar_field": "rgb(70, 70, 70)",
      "toolbar_field_text": "rgb(219, 220, 219)",
      "tab_line": "rgb(31, 31, 31)",
      "popup": "rgb(87, 87, 87)",
      "popup_text": "rgb(219, 220, 219)",
      "button_background_active": "rgb(121, 121, 121)",
      "button_background_hover": "rgb(222, 222, 222)",
      "frame_inactive": "rgb(51, 51, 51)",
      "icons_attention": "rgb(222, 222, 222)",
      "icons": "rgb(77, 77, 77)",
      "ntp_background": "rgb(242, 242, 242)",
      "popup_border": "rgb(198, 198, 198)",
      "popup_highlight": "rgb(171, 192, 198)",
      "sidebar_border": "rgb(171, 192, 198)",
      "tab_background_separator": "rgb(189, 189, 189)",
      "toolbar_field_border_focus": "rgb(251, 251, 251)",
      "tab_loading": "rgb(31, 31, 31)"
    }
  }
}