Corporate Pro includes 4 different button styles that can be used throughout the theme:
Default
<a class="button" href="https://example.com">Button Text</a>
Outline
<a class="button outline" href="https://example.com">Button Text</a>
White
<a class="button white" href="https://example.com">Button Text</a>
White Outline
<a class="button white outline" href="https://example.com">Button Text</a>