<button>button</button>
<input type="button" value="input" />
<input type="submit" value="submit input" />
<a href="#" class="btn">a.btn</a>

<button>Default</button>
<button class="primary">Primary</button>
<button class="secondary">Secondary</button>
<button class="success">Success</button>
<button class="warning">Warning</button>
<button class="danger">Danger</button>

<button class="small">Small</button>
<button>Normal</button>
<button class="large">Large</button>

<div class="btn-grp">
  <button>Default</button>
  <button>Default</button>
  <button>Default</button>
</div>

<button class="no-style">no-style</button>
<button class="no-btn">no-btn</button>