如何在bootstrap中创建一个透明的模式？

<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#myModal">打开模态框</button>

<div class="modal" id="myModal" style="background-color: transparent;">
  <div class="modal-dialog">
    <div class="modal-content">
      <!-- 模态框的内容 -->
    </div>
  </div>
</div>

<div class="modal" id="myModal" style="background-color: transparent;">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title">模态框标题</h5>
        <button type="button" class="close" data-dismiss="modal">&times;</button>
      </div>
      <div class="modal-body">
        <p>模态框的内容</p>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">关闭</button>
        <button type="button" class="btn btn-primary">保存</button>
      </div>
    </div>
  </div>
</div>

<script>
  $(document).ready(function(){
    $('#myModal').modal({
      backdrop: 'static',
      keyboard: false
    });
  });
</script>