JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="input-group">
    <input id="ban_time" type="number" class="form-control" value="10" style="width: auto">
    <select class="form-control" style="width: auto">
      <option selected="">seconds</option>
      <option>minutes</option>
      <option>hours</option>
      <option>days</option>
      <option>weeks</option>
    </select>
  </div>

</div>

CSS

@import url("https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css")