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