Большие кнопки
<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>
<button type="button" class="btn btn-outline-primary">Primary</button>
<button type="button" class="btn btn-outline-secondary">Secondary</button>
<button type="button" class="btn btn-outline-success">Success</button>
<button type="button" class="btn btn-outline-danger">Danger</button>
<button type="button" class="btn btn-outline-warning">Warning</button>
<button type="button" class="btn btn-outline-info">Info</button>
<button type="button" class="btn btn-outline-light">Light</button>
<button type="button" class="btn btn-outline-dark">Dark</button>
Маленькие кнопки
<button type="button" class="btn btn-primary btn-sm">Small button</button>
<button type="button" class="btn btn-secondary
btn-sm">Small button</button>
<button type="button" class="btn btn-success
btn-sm">Small button</button>
<button type="button" class="btn btn-danger
btn-sm">Small button</button>
<button type="button" class="btn btn-outline-primary btn-sm">Primary</button>
<button type="button" class="btn btn-outline-secondary btn-sm">Secondary</button>
<button type="button" class="btn btn-outline-success btn-sm">Success</button>
<button type="button" class="btn btn-outline-danger btn-sm">Danger</button>
<button type="button" class="btn btn-outline-warning btn-sm">Warning</button>
<button type="button" class="btn btn-outline-info btn-sm">Info</button>
<button type="button" class="btn btn-outline-light btn-sm">Light</button>
<button type="button" class="btn btn-outline-dark btn-sm">Dark</button>