JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/js/bootstrap.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css">

<div class="container">
  <div class="row">
    <form role="form">
      <div class="col-xs-8 col-sm-8">
        <label for="lab1">Longueur 1</label>
        <input type="text" class="form-control" id="lab1" value="12345678" />
      </div>
      <div class="col-xs-4 col-sm-2">
        <label for="lab2">Longueur 2</label>
        <input type="text" class="form-control" id="lab2" />
      </div>
      
    </form>
  </div>
</div>

CSS

label {
    text-align:center;
    background-color:red;
}

label:first-child {
    margin-top:0;
}