Tabindex
Element is focusable, but not reached with keyboard
<div tabindex="-1">Howdy</div>Element is focusable with the keyboard, it's order is defined by the document structure
<div tabindex="0">Howdy</div>Accordion markup
Accordion Markup - Sara Soueidan
<details>
<summary>What is the population of New Orleans?</summary>
According to 2010 Census Bureau estimates, New Orleans' population is made up of approximately 343,829 residents.
</details>details[open] summary {
color: red;
}Defining acronyms & abbreviations
dfn is the defining instance of a term (with the term being deinfed/explained in it's nearest parent). It can be used in conjunction with the abbr tag which defines an abbreviation or an acronym.
<p>The <dfn><abbr title="International Space Station">ISS</abbr></dfn> is a space station in low earth orbit.
</p>