Classes: button
Primary

<a class="button primary" href="#">Primary</a>

Classes: button small
Primary small

<a class="button primary small" href="#">Primary small</a>

Classes: button large
Primary large

<a class="button primary large" href="#">Primary large</a>

Classes: button hollow
Primary Hollow

<a class="button primary hollow" href="#">Primary Hollow</a>

Classes: button secondary
Secondary

<a class="button secondary" href="#">Secondary</a>

Classes: button secondary hollow
Secondary Hollow

<a class="button secondary hollow" href="#">Secondary Hollow</a>

Card title style button | Classes: button button-card | Fullwidth: expanded
Card title style button

<a class="button button-card" href="#"><span>Card title style button</span></a>

To expand buttons across the fullwidth add class expanded

<a class="button button-card expanded" href="#"><span>Card title style button</span></a>