Q:

figuring out why custom-element is shown in safari and firefox, but not in chrome

I've tried to figure out why the custom element  is shown in Safari and Firefox, but not in Chrome.  Neither in Canary nor in 35.0.1916.114. 
Shadow dom is enabled in flags. 
I've put together a fast jsBin:
http://jsbin.com/poracihi/4/

A:

This is because Chrome has native Shadow DOM support.  You're seeing the effect of the shadow dom boundary preventing the page's styles from bleeding in.  The solution is to include the styles inside your element's shadow dom: http://jsbin.com/poracihi/5/edit
Check out:
- http://www.html5rocks.com/en/tutorials/webcomponents/shadowdom-201/
- http://www.polymer-project.org/articles/styling-elements.html

