这是我的代码：
<div class="row">
<div class="col-md-3">
<h1 style="color:rgb(153,50,204)" class="visible-sm visible-xs" style="z-index:0; position:relative; "> Descriptions </h1>
<pre class="pre-scrollable" style="z-index:0;">
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另一个元素：
<div id="scroll" class="row img-responsive" style="z-index:10; position:relative; margin:0px;background-color: rgb(123,20,174); background-size:cover; background-position: center center;background-repeat: no-repeat;height:10vh;width:100%;">
滚动条具有较高的z索引，但在其他元素下。