关于css div带有滚动条，使用定位导致滚动条失效

<div style="position: relative;left: 0;top: 0;">
<div class="museum-info" style="position: absolute;">
<div class="museum-name">
<h3></h3>
</div>
<div class="museum-introduce" style="height:300px;overflow-y: auto;">
<p></p>
</div>
</div>
</div>

以上代码定位后导致子元素的滚动条失效，查了很多资料后都没解决，后来试着给 class=“museum-info” 加上z-index：1 后，问题解决，原因可能是在定位后该标签到了下层

<div style="position: relative;left: 0;top: 0;">
<div class="museum-info" style="position: absolute;z-index:1">
<div class="museum-name">
<h3></h3>
</div>
<div class="museum-introduce" style="height:300px;overflow-y: auto;">
<p></p>
</div>
</div>
</div>