Expand arrow gone from summary element
Created by: vanillajonathan
The visual expand arrow visible in Chrome and Firefox on the details
element disappears with normalize.
I don't know if this is intentional or not.
<details>
<summary>Click on this summary to expand</summary>
<p>Here is additional text, visible when expanded...</p>
</details>
Bootstrap 3.3.7 https://jsfiddle.net/vu6o29es/
Cross-reference: necolas/normalize.css#640