You can use any icon set but may require changing default icon variables. Default styles are intended for feather icons which is a great open source option.
icon
You can inject svg icons directly or use svg sprites. The only requirement is the icon component class.
<svg class="icon" role="img">
<use xlink:href="#icon-anchor"></use>
</svg>
icon_style_[key]
The default icon style is set using the $icon-style variable. You can also explicity style an icon using the style modifier.
<svg class="icon icon_style_stroke" role="img">
<use xlink:href="#icon-heart"></use>
</svg>
<svg class="icon icon_style_fill" role="img">
<use xlink:href="#icon-heart"></use>
</svg>