Examine source code of Steam (2020)

{
  "manifest_version": 2,
  "version": "2.0",
  "name": "Steam (2020)",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(22, 32, 45, 0.9)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(33, 60, 88)",
      "tab_background_text": "rgb(201, 207, 218)",
      "toolbar_field": "rgba(27, 39, 55, 0.85)",
      "toolbar_field_text": "rgb(233, 234, 235)",
      "tab_line": "rgb(43, 75, 105)",
      "popup": "rgb(27, 40, 56)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_active": "rgb(126, 166, 75)",
      "button_background_hover": "rgb(75, 142, 180)",
      "frame_inactive": "rgb(26, 48, 71)",
      "icons_attention": "rgb(102, 192, 244)",
      "icons": "rgb(255, 255, 255)",
      "ntp_background": "rgb(29, 48, 68)",
      "ntp_text": "rgb(255, 255, 255)",
      "popup_border": "rgb(27, 40, 56)",
      "popup_highlight_text": "rgb(33, 33, 33)",
      "popup_highlight": "rgb(126, 166, 75)",
      "sidebar_border": "rgb(27, 40, 56)",
      "sidebar_highlight_text": "rgb(102, 192, 244)",
      "sidebar_highlight": "rgb(43, 71, 94)",
      "sidebar_text": "rgb(255, 255, 255)",
      "sidebar": "rgb(27, 40, 56)",
      "tab_background_separator": "rgba(105, 0, 225, 0)",
      "tab_loading": "rgb(9, 185, 255)",
      "tab_selected": "rgb(43, 75, 105)",
      "tab_text": "rgb(255, 255, 255)",
      "toolbar_bottom_separator": "rgba(22, 32, 45, 0.9)",
      "toolbar_field_border_focus": "rgb(126, 166, 75)",
      "toolbar_field_border": "rgba(27, 39, 55, 0.85)",
      "toolbar_field_focus": "rgb(27, 40, 56)",
      "toolbar_field_highlight_text": "rgb(255, 255, 255)",
      "toolbar_field_highlight": "rgb(18, 102, 151)",
      "toolbar_field_separator": "rgba(105, 0, 225, 0)",
      "toolbar_field_text_focus": "rgb(255, 255, 255)",
      "toolbar_top_separator": "rgba(22, 32, 45, 0.9)",
      "toolbar_vertical_separator": "rgb(39, 47, 56)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5447f201-cdeb-42be-841c-fc1dfc23ed7e}"
    }
  }
}