Why bootstrap card-deck not working in bootstrap 5? [closed]

i tried card-deck class in boot strap …but it is not working …. can anybody help me in this > whats going on

<div class="card-deck">

      <!-- Persian Plan Card -->
      <div class="card">
        <div class="card-header text-center">
          <h3>Persian</h3>
        </div>
        <div class="card-body text-center">
          <h2 class="price-text">Free</h2>
          <p>5 Matches Per Day</p>
          <p>10 Messages Per Day</p>
          <p>Unlimited App Usage</p>
          <button class="btn btn-lg btn-block btn-outline-dark" type="button">Sign Up</button>
        </div>
      </div>
    
      <!-- Siamese Plan Card -->
      <div class="card">
        <div class="card-header text-center">
          <h3>Siamese</h3>
        </div>
        <div class="card-body text-center">
          <h2 class="price-text">$49 / mo</h2>
          <p>Unlimited Matches</p>
          <p>Unlimited Messages</p>
          <p>Unlimited App Usage</p>
          <button class="btn btn-lg btn-block btn-outline-dark" type="button">Sign Up</button>
        </div>
      </div>
    
      <!-- Maine Coon Plan Card -->
      <div class="card">
        <div class="card-header text-center">
          <h3>Maine Coon</h3>
        </div>
        <div class="card-body text-center">
          <h2 class="price-text">$99 / mo</h2>
          <p>Priority Listing</p>
          <p>Unlimited Matches</p>

          <p>Unlimited Messages</p>
          <p>Unlimited App Usage</p>
          <button class="btn btn-lg btn-block btn-outline-dark" type="button">Sign Up</button>
        </div>
      </div>
    
    </div>
    

I want this layout like this:

but I got this one: