Test HTML and CSS in Posts

From Custom css inside a post / adding custom classes - #3 by david - dev - Discourse Meta and What are the different ways to customize content inside a post (custom attributes and such) - support - Discourse Meta

div[data-theme-bot] {
  background-color: red;
}

<div data-theme-bot>
   Content here
</div>

Content here

From Tiles Image Gallery - #127 by Heather_Dudley - theme-component - Discourse Meta

cookie-monster
eyeball


tungsten-bulb

This is interesting, especially for images.