The <iframe> tag specifies an inline frame and is used to embed another document within the current HTML document.

iframes can be embedded into a Hugo Markdown document by wrapping it in a shortcode that allows raw HTML to be included.

There are some predefined Hugo shortcodes¹ for rendering certain types of content such as youtube videos, instagram, tweets etc. Otherwise you can create a custom shortcode.

(A Flask or Dash app can also be embedded as an iframe.)

Iframes include the following attributes:

• allowfullscreen: set to true to activate fullscreen mode.
• height in pixels
• loading to specify whether a browser should load an iframe immediately or to defer loading until some conditions are met. Options include eager or lazy.
• src to specify the address of the document to embed in the iframe.
• width in pixels, but can also be specified as a percentage.
• title to include a title
• style attribute to set CSS styling

By default an iframe has a border around it which can be removed by using the style attribute and setting the CSS border property to none. style="border:none;"

See www.w3schools.com ²

An iframe can be used as the target frame for a link.

Click the link to see a sample Dash app in the iframe above. My sample dash app

<iframe height='300' scrolling='yes' 
src="https://www.angela1c.com/projects" 
frameborder='no' allowtransparency='true' 
allowfullscreen='true' 
style='width: 100%'></iframe>

A plotly map: