tooltip, spoiler, dış-bağlantı iconu
<div class="btn-group">
<button type="button" class="btn btn-danger dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false"><br>
indir<br>
</button>
<div class="dropdown-menu">
<a class="dropdown-item" href="#">ePub</a><br>
<a class="dropdown-item" href="#">PDF</a><br>
<a class="dropdown-item" href="#">Mobi</a>
<div class="dropdown-divider"></div>
<p> <a class="dropdown-item" href="#">Nasıl okunur?</a>
</p>
</div>
</div>