Set negative action for Bootstrap 4 cards with red background color

To set negative action (danger) for cards with red background color, you need to use the Bootstrap contextual class card-danger.

Set the danger action −

<div class="card bg-danger">
  <div class="card-body">Danger! High Voltage!</div>
</div>

You can try to run the following code to set danger action for a card in Bootstrap 4 −

Example

Live Demo

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Bootstrap Example</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css">
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
  </head>

<body>
  <div class="container">
    <h2>Messages</h2>
    <div class="card">
      <div class="card-body">How you doing?</div>
    </div><br>
    <div class="card bg-danger">
      <div class="card-body">Danger! High Voltage!</div>
    </div><br>
  </div>

</body>
</html>