Demo button doesn't exist

[TarasH1]

Description

When i publish my code to webcomponents.org with demo page files there is no Demo button in Elements.

Live Demo

https://www.webcomponents.org/element/wise-shopping-cart

Expected Results

Demo button should be displayed

Actual Results

No Demo button

Browsers Affected

• Chrome
• Firefox
• Edge
• Safari
• IE 11

For example it's works for @polymer/paper-input:
https://i.imgur.com/vWccTbZ.png

[bohdaq]

+1 to this issue