A transient message in a corner region. The script shows the region, sets role="status" and closes the toast after timeout.
The toast region is a hidden popover until the script shows it, so the server also renders the message in the page as an al-alert:
With the script, each region is shown when its toast connects. These are sticky (timeout="0") so you can see all four variants at all four corners; the default timeout is 5000 ms and the toast closes itself. Text or a strong before the first block (div, p, list) is the title and the blocks are the description; a one-line message, even with inline elements, is all title. A toast with no variant has no icon.
post.mdA toast slides in from its region's edge and, when it closes, slides back out before it is removed (not with reduced motion). This one closes after 3000 ms.