Bootswatch / Bootstrap 4 dropdown and margin mistake

So I was playing around with the new Bootswatch based on Bootstrap 4 but somehow the "Cards" have no margin and the dropdown in the menu doesn't work. Can someone explain to me what I'm doing wrong here? Do I have to add the margin myself? And why doesn't the Dropdown work?

<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://bootswatch.com/4/cosmo/bootstrap.css">
</head>
<body>

<nav class="navbar navbar-expand-lg navbar-dark bg-primary">
<div class="container">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarColor01" aria-controls="navbarColor01" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarColor01">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Features</a>
      </li>
          <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="http://example.com" id="dropdown01" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Dropdown</a>
            <div class="dropdown-menu" aria-labelledby="dropdown01">
              <a class="dropdown-item" href="#">Action</a>
              <a class="dropdown-item" href="#">Another action</a>
            </div>
          </li>
    </ul>
  </div>
</div>
</nav>


<div class="container">
        <div class="row">
    <div class="col">
<div class="card">
  <div class="card-body">
    <h4 class="card-title">Card title</h4>
    <h6 class="card-subtitle mb-2 text-muted">Card subtitle</h6>
    <p class="card-text">Some quick example text to build on the card title and make <br>up the bulk of the card's content.</p>
    <a href="#" class="card-link">Card link</a>
    <a href="#" class="card-link">Another link</a>
  </div>
</div>
</div>
</div>
</div>

<script async src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.4/jquery.min.js"></script>
<script src="https://code.jquery.com/jquery-3.1.1.slim.min.js" integrity="sha384-A7FZj7v+d/sdmMqp/nOQwliLvUsJfDHW+k9Omg/a/EheAdgtzNs3hpfag6Ed950n" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>
</body>
</html>

Solution

The card margin doesn't have anything to do with this. The problem is with the JS.

I changed tether and Bootstrap alpha 6 JS to PopperJs and Bootstrap beta 2 JS. (see the Bootstrap docs)

I also added the class mt-3 to the container for some margin. Keep that if you want.

<!DOCTYPE html>
<html>

<head>
  <link rel="stylesheet" href="https://bootswatch.com/4/cosmo/bootstrap.css">
</head>

<body>

  <nav class="navbar navbar-expand-lg navbar-dark bg-primary">
    <div class="container">
      <a class="navbar-brand" href="#">Navbar</a>
      <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarColor01" aria-controls="navbarColor01" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
      <div class="collapse navbar-collapse" id="navbarColor01">
        <ul class="navbar-nav mr-auto">
          <li class="nav-item active">
            <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="#">Features</a>
          </li>
          <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="http://example.com" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Dropdown link
        </a>
            <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
              <a class="dropdown-item" href="#">Action</a>
              <a class="dropdown-item" href="#">Another action</a>
              <a class="dropdown-item" href="#">Something else here</a>
            </div>
          </li>
        </ul>
      </div>
    </div>
  </nav>


  <div class="container mt-3">
    <div class="row">
      <div class="col">
        <div class="card">
          <div class="card-body">
            <h4 class="card-title">Card title</h4>
            <h6 class="card-subtitle mb-2 text-muted">Card subtitle</h6>
            <p class="card-text">Some quick example text to build on the card title and make <br>up the bulk of the card's content.</p>
            <a href="#" class="card-link">Card link</a>
            <a href="#" class="card-link">Another link</a>
          </div>
        </div>
      </div>
    </div>
  </div>

  <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>
</body>

</html>