http://getbootstrap.com/getting-started/#download
위 링크에 가서 다운로드 받거나 페이지에 CDN을 추가한다.
<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css"> <!-- Optional theme --> <link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap-theme.min.css"> <!-- Latest compiled and minified JavaScript -->
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>
