<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwoIResjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">
<div class="container">
<div class="jumbotron"><h2>Buy a domain name</h2>
<div class="row">
<form method="post" name="formDomain" id="formDomain" action="?page=ajaxcheck">
<div class="input-group col-xs-5">
<input class="form-control form-control-lg" name="domain" id="domain" autocomplete="off" type="text" required="true">
<select name="dot" id="dot" class="custom-select form-control-lg dropdown-toggle">
<option value="fr">.fr</option>
<option value="com">.com</option>
<option value="eu">.eu</option>
<option value="org">.org</option>
</select>
</div><br />
<input value="Try" type="submit" id="tryDomain" name="tryDomain" class="btn btn-primary btn-lg btn-block">
</form>
</div>
</div>
</div>
<script src="https://code.jquery.com/jquery-2.1.4.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>