<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.0.8/css/all.css">
<div class="container">
<div class="row">
<aside class="col-sm-4">
<select class="mdb-select md-form colorful-select dropdown-primary" multiple searchable="Search here..">
<option value="" disabled selected>Choose your country</option>
<option value="1">USA</option>
<option value="2">Germany</option>
<option value="3">France</option>
<option value="3">Poland</option>
<option value="3">Japan</option>
</select>
<label class="mdb-main-label">Label example</label>
<select class="mdb-select" multiple searchable="Search here..">
<optgroup label="team 1">
<option value="1">Option 1</option>
<option value="2">Option 2</option>
</optgroup>
<optgroup label="team 2">
<option value="3">Option 3</option>
