* Remove duplicated code

* Revert "Remove duplicated code"

This reverts commit 26e2bd38c4497f2fd871c81b397d111b311f7bd5.

* Possibly fix issue

* Possibly fix sandbox issues

* Start adding overriding capabilities for already selected seats

* Update README.md

* Add tests for overriding occupied seats

* Fix linting issues, typo

* Update README.md

[skip ci]

[skip ci]

* Add tests for selecting seats

* Add tests for preventing selection of an occupied seat

* Possibly fix process exiting

* Update build order

* Namespace CSS classes

* Include custom-elements polyfill if needed

* More attempts at trying to fix polyfilling custom elements

* Fix the element in environments where custom elements are non-native

* Clean up the demo HTML

* Fix linting issues

[ci skip]