html - flex 元素不居中

Question

我有以下布局，其中填充了一个包含代表团队成员的圆圈的 div。对于由 >= 3 团队成员组成的团队，但对于仅由 1 || 组成的团队，目前我有一个奇怪的警告2 成员，圆圈对齐到容器的最左侧。

为什么会这样？

.fireteam {
  padding: 0 5px;
}

.fireteam>p {
  max-width: 100%;
  overflow: hidden;
  white-space: nowrap;
  margin: 0 0 0.1rem;
}

.fireteam #fireteamMembers {
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
  align-content: center;
  justify-content: center;
  height: 4.2rem;
  list-style: none;
  padding: 0;
  border: 1px solid #000;
  border-radius: 5px;
  overflow: hidden;
}

.fireteam .fireteamMember {
  width: 1.5rem;
  height: 1.5rem;
  background: #000;
  color: white;
  border-radius: 50%;
  margin: 0.25rem;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>

Answer 1

您的 flex 容器缺少 align-items: center。

将此添加到您的代码中:

.fireteam #fireteamMembers {
  align-items: center; /* NEW */
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
  align-content: center;
  justify-content: center;
  height: 4.2rem;
  list-style: none;
  padding: 0;
  border: 1px solid #000;
  border-radius: 5px;
  overflow: hidden;
}

.fireteam {
  padding: 0 5px;
}

.fireteam>p {
  max-width: 100%;
  overflow: hidden;
  white-space: nowrap;
  margin: 0 0 0.1rem;
}

.fireteam #fireteamMembers {
  align-items: center; /* NEW */
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
  align-content: center;
  justify-content: center;
  height: 4.2rem;
  list-style: none;
  padding: 0;
  border: 1px solid #000;
  border-radius: 5px;
  overflow: hidden;
}

.fireteam .fireteamMember {
  width: 1.5rem;
  height: 1.5rem;
  background: #000;
  color: white;
  border-radius: 50%;
  margin: 0.25rem;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" />
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>
<div class="fireteam col-xs-4">
  <p>name</p>
  <label>X members</label>
  <ul id="fireteamMembers">
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
    <li class="fireteamMember"></li>
  </ul>
</div>

在您的列方向容器中，一列中只能容纳两个圆圈。下一个包装。

一旦有了换行，容器就有了多条 flex 线，需要align-content让它们居中。你已经有了这个。这就是 >=3 起作用的原因。

但是当只有一两个圆圈时，只有一根flex线，align-content没有作用。这就是为什么 1 和 2 圆圈不居中的原因。您需要 align-items 将单行 flex 容器中的元素居中。

这里有一个更完整的解释:

• How does flex-wrap work with align-self, align-items and align-content?