Align the form to the center in Bootstrap 4 [duplicate]

I am trying to align the form to the center and keep it responsive. I have tried several ways but no success. I am trying to center all the text and the form. I am using Bootstrap v4. I am not sure if that helps.

HTML:

<section id="cover">
     <div id="cover-caption">
         <div id="container">
             <div class="col-sm-10 col-sm offset-1">
                 <h1 class="display-3">Welcome to Bootstrap 4</h1>
                 <div class="info-form">
                 <form action="" class="form-inline">
                    <div class="form-group">
                        <label class="sr-only">Name</label>
                        <input type="text" class="form-control" placeholder="Jane Doe">
                    </div>
                    <div class="form-group">
                        <label class="sr-only">Email</label>
                        <input type="text" class="form-control" placeholder="[email protected]">
                    </div>
                    <button type="submit" class="btn btn-success ">okay, go!</button>
                </form>
                </div>
                <br>

                <a href="#nav-main" class="btn btn-secondary-outline btn-sm" role="button">&darr;</a>
             </div>
         </div>
     </div>
 </section>

CSS:

html,
body{
 height: 100%;
}

#cover {
  background: #222 url('../img/stars.jpg') center center no-repeat;
  background-size: cover;
  color: white;
  height: 100%;
  text-align: center;
  display: flex;
  align-items: center;

}

#cover-caption {
  width: 100%;

}

You need to use the various Bootstrap 4 centering methods...

• Use text-center for inline elements.
• Use justify-content-center for flexbox elements (ie; form-inline)

https://codeply.com/go/Am5LvvjTxC

Also, to offset the column, the col-sm-* must be contained within a .row, and the .row must be in a container...

<section id="cover">
    <div id="cover-caption">
        <div id="container" class="container">
            <div class="row">
                <div class="col-sm-10 offset-sm-1 text-center">
                    <h1 class="display-3">Welcome to Bootstrap 4</h1>
                    <div class="info-form">
                        <form action="" class="form-inline justify-content-center">
                            <div class="form-group">
                                <label class="sr-only">Name</label>
                                <input type="text" class="form-control" placeholder="Jane Doe">
                            </div>
                            <div class="form-group">
                                <label class="sr-only">Email</label>
                                <input type="text" class="form-control" placeholder="[email protected]">
                            </div>
                            <button type="submit" class="btn btn-success ">okay, go!</button>
                        </form>
                    </div>
                    <br>

                    <a href="#nav-main" class="btn btn-secondary-outline btn-sm" role="button">↓</a>
                </div>
            </div>
        </div>
    </div>
</section>

<div class="d-flex justify-content-center align-items-center container ">

    <div class="row ">


        <form action="">
            <div class="form-group">
                <label for="inputUserName" class="control-label">Enter UserName</label>
                <input type="email" class="form-control" id="inputUserName" aria-labelledby="emailnotification">
                <small id="emailnotification" class="form-text text-muted">Enter Valid Email Id</small>
            </div>
            <div class="form-group">
                <label for="inputPassword" class="control-label">Enter Password</label>
                <input type="password" class="form-control" id="inputPassword" aria-labelledby="passwordnotification">

            </div>
        </form>

    </div>

</div>