Css 仅对一个子级使用引导顺序类来操作顺序

我在玩flexbox和bootstrap，我希望使用order类和一些js来制作某种“pin post to top”系统，但我遇到了一个问题

问题：显然，order类只有在所有孩子都有order类的情况下才能正常工作

工作：

<h3>Each DIVS has order class</h3>
<div class="d-flex bg-light border mb-4">
<div class="p-5 bg-info rounded m-3 text-center font-weight-bold h1 order-2">1</div>
<div class="p-5 bg-info rounded m-3 text-center font-weight-bold h1 order-3">2</div>
<div class="p-5 bg-info rounded m-3 text-center font-weight-bold h1 order-1">3</div>
</div>

<h3>Only one DIV has order class</h3>
<div class="d-flex bg-light border mb-4">
<div class="p-5 bg-danger rounded m-3 text-center font-weight-bold h1">1</div>
<div class="p-5 bg-danger rounded m-3 text-center font-weight-bold h1">2</div>
<div class="p-5 bg-danger rounded m-3 text-center font-weight-bold h1 order-1">3</div>
</div>

每个div都有订单类
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2.
3.

不工作：

<h3>Each DIVS has order class</h3>
<div class="d-flex bg-light border mb-4">
<div class="p-5 bg-info rounded m-3 text-center font-weight-bold h1 order-2">1</div>
<div class="p-5 bg-info rounded m-3 text-center font-weight-bold h1 order-3">2</div>
<div class="p-5 bg-info rounded m-3 text-center font-weight-bold h1 order-1">3</div>
</div>

<h3>Only one DIV has order class</h3>
<div class="d-flex bg-light border mb-4">
<div class="p-5 bg-danger rounded m-3 text-center font-weight-bold h1">1</div>
<div class="p-5 bg-danger rounded m-3 text-center font-weight-bold h1">2</div>
<div class="p-5 bg-danger rounded m-3 text-center font-weight-bold h1 order-1">3</div>
</div>

只有一个DIV具有订单类
1.
2.
3.

问题：如果只有一个子类作为order类，有没有办法让order类工作？提前感谢您

Bootstrap有一个解决方案：

先订购

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