证明内容不起作用-Flexbox问题

Question

我正在处理以下代码：

list

List<? extends E>

如您所见，justify-content属性不起作用。

好吧，我需要一些帮助，谢谢：）

Answer 1

如果您的意思是使按钮位于标题下方：

 .positiones {
  display: flex;
  height: 100vh;
  align-items: center;
  justify-content: center;
}
.button {
  display:block;
  margin: 0 auto 0 auto;
  width: 100px;
}

<div class="positiones">
  <div>
    <h1>The biggest startup event of the year!</h1>
    <button class="button" type="button" class="btn btn-primary btn-lg">Get more info</button>
  </div>
</div>

Answer 2

.button不在.positiones内。我放在.positiones里面。然后我添加flex-direction:column

.positiones {
  display: flex;
  height: 100vh;
  align-items: center;
  justify-content: center;
  flex-direction:column;
}

<div class="positiones">
  <div class="mainheading">
    <h1>The biggest startup event of the year!</h1><br>
  </div>
  <div class="Button">
  <button type="button" class="btn btn-primary btn-lg">Get more info</button><br>
</div>
</div>
<div class="linebreak"></div><br>