image-alt
For Quarto websites, blog posts, and HTML pages, you can include an image in the metadata that will be displayed in places such as the thumbnail for blog posts (like each of the tips on this site), and the preview card on social media.
You can (and should) provide alt text for these images by using the image-alt option in your YAML as well. For example, here’s a snippet from the YAML for the tip on using dark mode.
title: "Dark mode"
image: "featured.gif"
image-alt: "Switching between light and dark mode using the toggle on the navbar of this blog's homepage."Learn more
Note that image-alt can be supplied in several different places where an image can be specified, but that these will be inherited from the site or page metadata, so need not be repeated.