如何将图标对齐到 div 元素内的中心？

Question

我想将图标居中到 div 元素“矩形”。也欢迎任何其他替代解决方案。

body {
  background-color: black;
}

.rectangle {
  width: 125px;
	height: 125px;
	-webkit-border-radius: 5px;
	-moz-border-radius: 5px;
	border-radius: 5px;
	background-color: #fff;
}

h3 {
  color: #fff;
}

<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet"/>
<div class="rectangle">
  <span><i class="fa fa-quora" aria-hidden="true" style="font-size: 75px;" align="center"></i></span>
</div>
<h3>Quora</h3>

Answer 1

添加position: relative;到.rectangle和图标下面的CSS：

.fa-quora {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  }

.fa-quora {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  }

body {
  background-color: black;
}

.rectangle {
    width: 125px;
	height: 125px;
	-webkit-border-radius: 5px;
	-moz-border-radius: 5px;
	border-radius: 5px;
	background-color: #fff;
    position: relative;
}
.fa-quora {
   position: absolute;
   top: 50%;
   left: 50%;
   transform: translate(-50%, -50%);
}
h3 {
   color: #fff;
}

Answer 2

通过将其添加到您的.rectangle班级

display: flex;
justify-content: center;
align-items: center;

示例片段

display: flex;
justify-content: center;
align-items: center;

body {
  background-color: black;
}

.rectangle {
  width: 125px;
	height: 125px;
	-webkit-border-radius: 5px;
	-moz-border-radius: 5px;
	border-radius: 5px;
	background-color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
}

h3 {
  color: #fff;
}

如果您想支持旧浏览器，请将其添加到您的.rectangle课程中

display: table-cell;
text-align: center;
vertical-align: middle;

示例片段

<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet"/>
<div class="rectangle">
  <span><i class="fa fa-quora" aria-hidden="true" style="font-size: 75px;" align="center"></i></span>
</div>
<h3>Quora</h3>

display: table-cell;
text-align: center;
vertical-align: middle;