bootstrap b4 button code example
Example 1: bootstrap 4 button
<button type="button" class="btn btn-primary">Primary</button>
<button type="button" class="btn btn-secondary">Secondary</button>
<button type="button" class="btn btn-success">Success</button>
<button type="button" class="btn btn-danger">Danger</button>
<button type="button" class="btn btn-warning">Warning</button>
<button type="button" class="btn btn-info">Info</button>
<button type="button" class="btn btn-light">Light</button>
<button type="button" class="btn btn-dark">Dark</button>
<button type="button" class="btn btn-link">Link</button>
Example 2: btn-default class in bootstrap 4
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<div class="container m-3">
<a class="btn btn-outline-secondary">outline-secondary link</a>
<button type="button" class="btn btn-outline-secondary">outline-secondary 'button'</button>
<br><br>
<a class="btn btn-outline-light">outline-light link</a>
<button type="button" class="btn btn-outline-light">outline-light 'button'</button>
</div>