JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-2.1.4.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/select2/4.0.0/css/select2.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/select2/4.0.0/js/select2.min.js"></script>
<div class="container">
<div class="container-fluid">
   <form>
       <fieldset>
    <div class="col-sm-7">
      <div class="form-group">
        <label for="exampleInputEmail1">Email address</label>
        <input type="email" class="form-control" id="exampleInputEmail1" placeholder="Email">
     </div>
     <div class="form-group">
       <label for="exampleInputPassword1">Password</label>
       <select class="select2" width="100%">
           <option value="1">a</option>
           <option value="2">b</option>
           <option value="3">c</option>
           <option value="4">Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</option>
         </select>
     </div>
  
   
  </div>
  <div class="col-sm-5">
      <img...

CSS

fieldset {
    border: 1px solid #ddd;
    border-radius: 4px;
    margin-top: 15px;
    padding-top: 15px;
}

.select2-container {
    width: 100% !important;
}

/*! Select2 Bootstrap Theme v0.1.0-beta.4 | MIT License | github.com/select2/select2-bootstrap-theme */.select2-container--bootstrap .select2-search--dropdown .select2-search__field,.select2-container--bootstrap .select2-selection{-webkit-box-shadow:inset 0 1px 1px rgba(0,0,0,.075);border:1px solid #ccc;background-color:#fff;color:#555;font-family:"Helvetica Neue",Helvetica,Arial,sans-serif}.select2-container--bootstrap{display:block}.select2-container--bootstrap .select2-selection{box-shadow:inset 0 1px 1px rgba(0,0,0,.075);border-radius:4px;font-size:14px;outline:0}.select2-container--bootstrap .select2-search--dropdown .select2-search__field{box-shadow:inset 0 1px 1px rgba(0,0,0,.075);border-radius:4px;font-size:14px}.select2-container--bootstrap .select2-search__field{outline:0}.select2-container--bootstrap .select2-search__field::-webkit-input-placeholder{color:#999}.select2-container--bootstrap .select2-search__field:-moz-placeholder{color:#999}.select2-container--bootstrap .select2-search__field::-moz-placeholder{color:#999;opacity:1}.select2-container--bootstrap .select2-search__field:-ms-input-placeholder{color:#999}.select2-container--bootstrap .select2-results__option[role=group]{padding:0}.select2-container--bootstrap .select2-results__option[aria-disabled=true]{color:#777;cursor:not-allowed}.select2-container--bootstrap .select2-results__option[aria-selected=true]{background-color:#f5f5f5;color:#262626}.select2-container--bootstrap .select2-results__option--highlighted[aria-selected]{background-color:#337ab7;color:#fff}.select2-container--bootstrap .select2-results__option .select2-results__option{padding:6px 12px}.select2-container--bootstrap .select2-results__option .select2-results__option .select2-results__group{padding-left:0}.select2-container--bootstrap .select2-results__option...

JavaScript

$(function(){
$.fn.select2.defaults.set('theme', 'bootstrap');
$('.select2').select2({
	minimumResultsForSearch: Infinity
  });
});