how to center form using bootstrap 4

Question

I just learned bootstrap and try to centered a form using bootstrap 4 but seems keep failing. I've try put container, margin auto, grid, etc but still failing.

Here is the last code using bootstrap grid.

<form class="col-lg-6 offset-lg-3">
    <div class="row">
        <input type="text" placeholder="Example input">
        <span class="input-group-btn">
            <button class="btn btn-primary">Download</button>
        </span>
    </div>
</form>

and here is the link https://jsfiddle.net/artjia/emsw7t93/

Answer 1

used justify-content-center

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" rel="stylesheet"/>
 <form class="col-lg-6 offset-lg-3 ">
   <div class="row justify-content-center">
     <input type="text" placeholder="Example input">
     <span class="input-group-btn">
       <button class="btn btn-primary">Download</button>
     </span>
   </div>
 </form>

Answer 2

Use the css class justify-content-center. offset-col-* css class doesn t exist anymore in V4 bootstrap. Now it uses flex grid.

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" rel="stylesheet"/>
<div class="container">
  <div class="row justify-content-center">
    <div class="col-6">
     <form>
      <input type="text" placeholder="Example input">
      <span class="input-group-btn">
        <button class="btn btn-primary">Download</button>
      </span>
     </form>
     </div>
  </div>
</div>

For more info, consult the documentation => https://v4-alpha.getbootstrap.com/layout/grid/#horizontal-alignment

Et voilà.