<p class="h1 text-center">Retirar estoque</p>
<div class="container">
  <div class="">
    <div class="mb-3">
      <a href="#/codigodebarras" type="button" id="voltar" class="btn btn-info btn-lg btn-block">Voltar </a>
    </div>
  </div>
 <div class="">
  <div class="mb-3">
    <div id="camera" style="text-align: center;">
    </div>
  </div>
 </div>
</div>
<style>
  #camera > video:nth-child(1){
    width: 100%;
  }
  .drawingBuffer{
  	width: 100%;	
  }
</style>