A Collection of Custom UI Elements in Vanilla Javascript

Dependency-free and fairly simple ui widgets (some of which should probably not be widgets at all, but here we are).

Goals for each are:

1. to conform to the Custom Elements Specification,
2. to be styleable with .css in the normal way,
3. to be themeable via document.documentElement.setAttribute("window-theme", "theme-name");
4. to be easy and sane to use

Would love to receive any feedback, issues, or contributions!

Custom HTML Elements:

ApplicationWindow demo
CodeArea demo
Menus demo
SpinBox demo