什么 CSS 属性 在 Bootstrap 4 模式的背景中禁用 activity?

What CSS property disables the activity in the background of a Bootstrap 4 modal?

我想知道什么 属性 或属性集可用于停用、模糊甚至使 Bootstrap 模式后面的背景变暗。

我有兴趣在其他地方使用这些相同的属性,但在使用检查元素(开发人员工具)时找不到它们。

希望大家帮帮忙。提前致谢!

A div .modal-backdrop 被创建,它负责这个...玩来改变这个 div

的颜色或不透明度

.modal-backdrop {
  background: rgba(161, 247, 174, 0.9) !important;
  opacity: 0.3 !important;
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>


<div class="container">
  <h2>Modal Example</h2>
  <!-- Button to Open the Modal -->
  <button type="button" class="btn btn-primary" data-toggle="modal" data-target="#myModal">
    Open modal
  </button>

  <!-- The Modal -->
  <div class="modal" id="myModal">
    <div class="modal-dialog">
      <div class="modal-content">

        <!-- Modal Header -->
        <div class="modal-header">
          <h4 class="modal-title">Modal Heading</h4>
          <button type="button" class="close" data-dismiss="modal">&times;</button>
        </div>

        <!-- Modal body -->
        <div class="modal-body">
          Modal body..
        </div>

        <!-- Modal footer -->
        <div class="modal-footer">
          <button type="button" class="btn btn-danger" data-dismiss="modal">Close</button>
        </div>

      </div>
    </div>
  </div>

</div>