■ 公式サイト
https://getbootstrap.com/docs/4.1/components/buttons/https://getbootstrap.com/docs/4.1/components/button-group/
■ サンプル
<!doctype html>
<html lang="jp">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
<!-- Font Awesome -->
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.2.0/css/all.css" integrity="sha384-hWVjflwFxL6sNzntih27bfxkr27PmbbK/iSvJ+a4+0owXq79v+lsFkW54bOGbiDQ" crossorigin="anonymous">
<title>Hello, world!</title>
</head>
<body>
<!-- アイコン -->
<i class="fa fa-trash-alt"></i><br>
<i class="fa fa-pencil-alt"><br>
<br>
<!-- ボタン -->
<a class="btn" href="#">Default</a><br>
<a class="btn btn-primary" href="#">Primary</a><br>
<a class="btn btn-info" href="#"><i class="glyphicon glyphicon-info-sign"></i> Info</a><br>
<div class="btn-group">
<a class="btn btn-success" href="#">Success</a>
<a class="btn btn-warning" href="#">Warning</a>
<a class="btn btn-danger" href="#">Danger</a>
</div>
<br>
<button type="button" class="btn btn-dark rounded-circle shadow"><i class="fa fa-trash-alt mt-0"></i></button><br>
<button type="button" class="btn btn-outline-primary btn-sm rounded-circle shadow-lg"><i class="fa fa-pencil-alt mt-0"></i></button><br>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js" integrity="sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" crossorigin="anonymous"></script>
</body>
</html>
