If you have text content that you want to stand out in a certain way, it's possible to create something we call "labels". This is very similar to bootstrap labels (see Bootstrap badges and labels), and in fact the HTML5 output creates just such labels. However, it works in PDF as well.
Example 38. Example labels
Default label Primary label Success label Info label Warning label Danger label
These can be used for any purpose you need, and the names are only markers that will create a label of the designated color. You should not use these instead of proper admonitions (