Examine source code of dark gray mix

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "dark gray mix",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(103, 103, 103)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(103, 103, 103)",
      "tab_background_text": "rgb(225, 225, 225)",
      "toolbar_field": "rgb(0, 130, 153)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(13, 168, 176)",
      "popup": "rgb(13, 168, 176)",
      "popup_text": "rgb(34, 34, 34)",
      "button_background_hover": "rgb(0, 130, 153)",
      "icons": "rgb(52, 222, 179)",
      "ntp_background": "rgba(108, 108, 108, 0.5)",
      "ntp_text": "rgb(255, 255, 255)",
      "popup_border": "rgb(0, 0, 0)",
      "sidebar_border": "rgb(13, 168, 176)",
      "sidebar_highlight_text": "rgb(52, 222, 179)",
      "sidebar_highlight": "rgba(108, 108, 108, 0.5)",
      "sidebar_text": "rgb(255, 255, 255)",
      "sidebar": "rgb(44, 44, 44)",
      "tab_selected": "rgb(103, 103, 103)",
      "tab_text": "rgb(255, 255, 255)",
      "toolbar_field_border_focus": "rgb(44, 44, 44)",
      "toolbar_field_highlight": "rgb(52, 222, 179)",
      "tab_loading": "rgb(13, 168, 176)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{64d607da-200e-4d95-87e2-f84f3962c96c}"
    }
  }
}