Examine source code of Old Steam

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Old Steam",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(76, 88, 68)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(62, 70, 55)",
      "tab_background_text": "rgb(196, 181, 80)",
      "toolbar_field": "rgb(62, 70, 55)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(128, 128, 128)",
      "popup": "rgb(76, 88, 68)",
      "popup_text": "rgb(255, 255, 255)",
      "popup_highlight": "rgba(196, 181, 80, 0.3)",
      "button_background_active": "rgb(196, 181, 80)",
      "button_background_hover": "rgba(196, 181, 80, 0.3)",
      "icons_attention": "rgb(196, 181, 80)",
      "ntp_background": "rgb(62, 70, 55)",
      "ntp_card_background": "rgb(76, 88, 68)",
      "ntp_text": "rgb(255, 255, 255)",
      "popup_border": "rgb(128, 128, 128)",
      "sidebar_border": "rgb(128, 128, 128)",
      "sidebar_highlight": "rgb(196, 181, 80)",
      "sidebar_text": "rgb(196, 181, 80)",
      "sidebar": "rgb(62, 70, 55)",
      "tab_background_separator": "rgb(128, 128, 128)",
      "tab_selected": "rgb(196, 181, 80)",
      "tab_text": "rgb(0, 0, 0)",
      "toolbar_bottom_separator": "rgb(128, 128, 128)",
      "toolbar_field_border_focus": "rgb(196, 181, 80)",
      "toolbar_field_border": "rgb(128, 128, 128)",
      "toolbar_field_highlight_text": "rgb(0, 0, 0)",
      "toolbar_field_highlight": "rgb(196, 181, 80)",
      "toolbar_field_separator": "rgb(128, 128, 128)",
      "toolbar_field_text_focus": "rgb(255, 255, 255)",
      "toolbar_top_separator": "rgb(128, 128, 128)",
      "toolbar_vertical_separator": "rgb(128, 128, 128)",
      "tab_loading": "rgb(128, 128, 128)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e9ad81c7-0092-4c47-8b31-56aa8e6bbfa6}"
    }
  }
}