如何在一行中的两列中显示ul列表？

I have the list as below:

我有以下列表:

<div class="ListStyle">
   <ul>
      <li>List1
         <ul> 
            <li>ChildList1</li>
            <li>ChildList2</li>
         </ul>
      </li>
      <li>List2
           <ul> 
            <li>ChildList1</li>
           </ul>
      </li>
   </ul>
</div
<div clas