bootstrap button drak

The .btn classes are designed to be used with the <button> element. 
However, you can also use these classes on <a> or <input> elements
(though some browsers may apply a slightly different rendering).

When using button classes on <a> elements that are used to trigger in-page 
functionality (like collapsing content), rather than linking to new pages or 
sections within the current page, these links should be given a role="button" 
to appropriately convey their purpose to assistive technologies such as screen 
readers.

<a class="btn btn-primary" href="#" role="button">Link</a>
<button class="btn btn-primary" type="submit">Button</button>
<input class="btn btn-primary" type="button" value="Input">
<input class="btn btn-primary" type="submit" value="Submit">
<input class="btn btn-primary" type="reset" value="Reset">

 <button type="button" class="btn btn-primary btn-block">Full-Width 
  Button</button> 

<button type="button" class="btn btn-dark">Dark</button>