JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap-theme.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>

    <title>Example of navbar overflow</title>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>


  <body data-spy="scroll" data-target="#navbar-example">
    <div class="row">
      <div class="container">
        <div class="col-sm-3">
          <div class="sidenav" id="navbar-example">
            <ul class="nav nav-pills nav-stacked" data-spy="affix" data-offset-top="1">
              <li><a href="#headline0">Section 1</a></li>
              <li><a href="#headline1">Section 2 - a very very long thing</a></li>
              <li><a href="#headline2">Section 3</a></li>
            </ul>
          </div>
        </div>
        <div class="col-sm-9">
          <div id="headline0">
            <h1>Section 1</h1></div>
          <p>
            blah </p>
          <div id="headline1">
            <h2>Section 2</h2></div>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <p> blah blah blah blah </p>
          <div id="headline2">
            <h2>Section 3</h2>
            <p> blah blah blah blah </p>
            <p> blah blah blah blah...

CSS

.nav.affix {
  max-width: 145px;
}