Icon Library

I am looking at the Hugo Website, I have a question on the icons used in index.html, e.g. icon-idea,
icon-arrow-down, icon-talking, icon-circlestar etc.

Which is the Icon Library used by the default Hugo theme (website) and can I modify it to use Bootstrap or Material Design or Font Awesome Icons.

http://www.w3schools.com/w3css/w3css_icons.asp

Thanks,
Rajesh

I have the answer, the icons are defined in the hugofont.css and I was able to change it to use Google Fonts.

thanks, Rajesh