Short callouts are useful for brief lines of information that should appear close to the preceding paragraph.
They follow the normal syntax for callouts and are characterized by the fact that their type identifier ends with a colon (:). I like to use them for source references. 
> [!book-copy:] See also
> HIBBELER, Russell C., 2023. _Mechanics of Materials, SI Edition_.
Also useful as simple headers for project notes.
Some useful default types are already predefined:
In order to customize icons, colors and type identifiers just edit the snippet or - even simpler - use the awesome Callout Manager plugin.
As they are normal callouts, they can also be folded using the + - syntax.
Download and usage instructions: GitHub - ltroj/obsidian-short-callout: CSS snippet for short callouts in Obsidian.md
Hope you can make use of it!