Details

aka Accordion UI, Expansion panel

summary title detailed info that unravels and folds
<details open>
  <summary>summary title</summary>

  detailed info that unravels and folds
</details>

Styling

hide triangular marker

summary::-webkit-details-marker, summary::marker {
  display: none;
}

Examples

Flexbox footer

More info

The details and summary elements, again - scottohara.me