Source: dist/css/virtual_boot.css, line 21548
2.5 Button and Link Failure On No Href
The button and link will auto style when the href is empty.
Example
Default styling
<a href="" class="btn br_radius max-w_30 m_auto m-b_3 block shadow_overlap-light btn-primary c_white h:undecorated" target="_blank">Button</a>
<a href="https://www.facebook.com/AmericanCollegeofCardiology/" class="btn br_radius max-w_30 m_auto m-b_3 block shadow_overlap-light btn-primary c_white h:undecorated" target="_blank">Button</a>
<a href="" class="link" target="_blank">Text Link</a>
<a href="https://www.facebook.com/AmericanCollegeofCardiology/" class="link" target="_blank">Text Link</a>