Material Design Lite theme
This theme integrate Google's light-weight implementation of Material Design, using SASS to keep compatibility with existing Liferay portlets.
Material Design Lite (getmdl.io) is used in various Google sites, and it's open source. The Download Kit is available for use in any portlet. getmdl.io/customize can be used to replace material.css
See a video, https://youtu.be/w0J4Qva8Me4