Html Bootstrap Grid System col 无法正常工作

您忘记根据您正在查看的屏幕大小来设置您的列类.这样，在中等屏幕尺寸上制作2列，在小屏幕上使用col-md-6 col-sm-12

<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin="anonymous">

    <div class="container">
        <div class="row">
            <!--Product: banana split-->
            <div class="col-md-6 col-sm-12">
                <div class="card" style="width: 20rem;">
                    <img class="card-img-top" src="img/banana-split.png" alt="Banana Split Image">
                    <div class="card-block">
                        <h4 class="card-title">Banana Split</h4>
                        <p class="card-text">Price: 5$</p>
                        <a href="#" data-name="banana-split" data-price="5" class="add-to-cart btn btn-primary"><i class="fas fa-shopping-cart"></i> Add to Cart</a>
                    </div>
                </div>
            </div>

            <div class="col-md-6 col-sm-12">
                <div class="card" style="width: 20rem;">
                    <img class="card-img-top" src="img/bengala-doce.png" alt="Bengala Doce Image">
                    <div class="card-block">
                        <h4 class="card-title">Doce Natalino</h4>
                        <p class="card-text">Price: 2$</p>
                        <a href="#" data-name="doce-natalino" data price="3" class="add-to-cart btn btn-primary"> <i class="fas fa-shopping-cart"></i> Add to Cart</a>
                    </div>
                </div>
            </div>
        </div>
    </div>