Examine source code of Grey and Minimal

{
  "manifest_version": 2,
  "version": "2.0",
  "name": "Grey theme v2.0",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-013-06591d4ad28ab7b9ee90f62f81d6b505.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(67, 67, 67)",
      "toolbar_text": "rgb(227, 227, 227)",
      "frame": "rgb(34, 34, 34)",
      "tab_background_text": "rgb(227, 227, 227)",
      "toolbar_field": "rgb(34, 34, 34)",
      "toolbar_field_text": "rgb(227, 227, 227)",
      "tab_line": "rgb(34, 34, 34)",
      "popup": "rgb(67, 67, 67)",
      "popup_text": "rgb(227, 227, 227)",
      "ntp_background": "rgb(67, 67, 67)",
      "ntp_text": "rgb(227, 227, 227)",
      "popup_border": "rgb(227, 227, 227)",
      "sidebar_border": "rgb(227, 227, 227)",
      "sidebar_highlight_text": "rgb(67, 67, 67)",
      "sidebar_text": "rgb(227, 227, 227)",
      "sidebar": "rgb(67, 67, 67)",
      "tab_loading": "rgb(227, 227, 227)",
      "toolbar_bottom_separator": "rgb(67, 67, 67)",
      "toolbar_field_border_focus": "rgb(227, 227, 227)",
      "toolbar_field_border": "rgb(227, 227, 227)",
      "toolbar_field_focus": "rgb(67, 67, 67)",
      "toolbar_top_separator": "rgb(227, 227, 227)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{66c31555-5068-471c-9905-f64fbb56ee37}"
    }
  }
}