Bootstrap card header: div class= card-header card-header-warning

Question

当我在一个页面上通过复制和粘贴完全相同的代码来使用一些引导卡时，我遇到了一个问题，因为我想要显示两个卡是相同的。

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<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet"/>
<div class="row">
  <div class="col-md-4">
    <div class="card card-chart">
      <div class="card-header card-header-warning">
        <div class="ct-chart" id="websiteViewsChart"></div>
      </div>
      <div class="card-body">
        <h4 class="card-title">Policies</h4>
        <p class="card-category"></p>
      </div>
      <div class="card-footer">
        <div class="stats">
          <p>Policies Graph</p>
        </div>
      </div>
    </div>
  </div>

  <div class="col-md-4">
    <div class="card card-chart">
      <div class="card-header card-chart card-header-warning">
        <div class="ct-chart" id="websiteViewsChart"></div>
      </div>
      <div class="card-body">
        <h4 class="card-title">Policies</h4>
        <p class="card-category"></p>
      </div>
      <div class="card-footer">
        <div class="stats">
          <p>Policies Graph</p>
        </div>
      </div>
    </div>
  </div>
</div>

​

第一个是显示，第二个是缺少一些设计，请看看代码和输出，如果你回答我谢谢我会很高兴。

​

Answer 1

我检查了下面的代码，并添加了flex命令来居中两张牌+虚拟图像，以替换包含在图片中但不包含在代码中的图表。最终的代码如下所示

<div class="row justify-content-center">
    <div class="col-md-4" >
        <div class="card card-chart">
            <div class="card-header card-header-warning">
                <div class="ct-chart text-center" id="websiteViewsChart">
                    <img  src="https://dummyimage.com/200x200/000/fff" alt="Rock And Roll">
                </div>
            </div>
            <div class="card-body">
                <h4 class="card-title">Policies</h4>
                <p class="card-category"></p>
            </div>
            <div class="card-footer">
                <div class="stats">
                    <p>Policies Graph</p>
                </div>
            </div>
        </div>
    </div>

    <div class="col-md-4" >
        <div class="card card-chart">
            <div class="card-header card-chart card-header-warning">
                <div class="ct-chart text-center" id="websiteViewsChart">
                    <img src="https://dummyimage.com/200x200/000/fff" alt="Rock And Roll">
                </div>
            </div>
            <div class="card-body">
                <h4 class="card-title">Policies</h4>
                <p class="card-category"></p>
            </div>
            <div class="card-footer">
                <div class="stats">
                    <p>Policies Graph</p>
                </div>
            </div>
        </div>
    </div>
</div>