<ceb/> was initially a library dedicated for the authoring of Custom Elements (v0) then Custom Elements (v1).
However, the library is now providing building blocks going beyond the topic of composable UI elements.
It's about fundamental design principles, messaging, functional rendering and obviously composition of UI elements ;).
<ceb/> is released under the MIT license.
The source code is available on GitHub: github.com/tmorin/ceb.