bootstrap 4 anchor style code example
Example 1: bootstrap button outline
<button type="button" class="btn btn-outline-primary" href="#">Primary</button>
Example 2: bootstrap button drak
<button type="button" class="btn btn-dark">Dark</button>
<button type="button" class="btn btn-outline-primary" href="#">Primary</button>
<button type="button" class="btn btn-dark">Dark</button>