Hugo uses Markdown for its simple content format. However, there are a lot of things that Markdown doesn’t support well. You could use pure HTML to expand possibilities.
But this happens to be a bad idea. Everyone uses Markdown because it’s pure and simple to read even non-rendered. You should avoid HTML to keep it as simple as possible.
To avoid this limitations, Hugo created shortcodes. A shortcode is a simple snippet inside a page.
The Relearn theme provides multiple shortcodes on top of existing ones.
List of files attached to a page
List the child pages of a page
Expandable/collapsible sections of text
Displays content from other files
Beautiful math and chemical formulae
Generate diagrams and flowcharts from text
Disclaimers to help you structure your page
Get value of site params
UI for your Swagger / OpenAPI Specifications
Show content in tabbed views