Check this post written by Chris Coyier on mailto: links. "It's pretty easy to use, but as with anything web, there are lots of things to consider."
You may also be interested in ...
1 line layouts
10 Modern CSS layout and sizing techniques that highlight just how robust and impactful a single-line of styling code can be.
Shoelace
A collection of open source, professionally designed UI components built on a framework-agnostic technology.
StandardJS
SyandardJS is a JavaScript style guide, linter, and formatter made by Feross Aboukhadijeh.
