中心跨度垂直

Question

我有这段代码：

a {
  background: #A9A9A9;
  display: block;
  position: absolute;
  right: 0;
  top: 0;
  height: 100%;
  width: 20%;
  vertical-align: middle;
  float: right;
  text-align: center;
}
a span {
  display: inline-block;
  vertical-align: middle;
}

<a href="#"><span>Center</span></a>

我想将span垂直居中到a中的position: absolute;。

Answer 1

使用position:relative来跨越top:50%

a {
	background: #A9A9A9;
	display: block;
    position: absolute;
    right: 0;
    top: 0;
    height: 100%;
    width: 20%;
    vertical-align: middle;
	float: right;
	text-align: center;
}

a span {
    display: inline-block;
    position: relative;
    top: 50%;
    transform: translate(0px, -50%);
}

<a href="#"><span>Center</span></a>

解决方案2：

使用display:table和display:table-cell。

a {
  background: #A9A9A9;
  display: block;
  position: absolute;
  right: 0;
  top: 0;
  height: 100%;
  width: 20%;
  vertical-align: middle;
  float: right;
  text-align: center;
  display:table;
}
a span {
  display: table-cell;
  vertical-align: middle;
}

<a href="#"><span>Center</span></a>

Answer 2

Flexbox的大用途。只需确保检查供应商前缀和broswer支持：

https://css-tricks.com/snippets/css/a-guide-to-flexbox/

a {
	background: #A9A9A9;
	display: flex;
    justify-content: center;
    align-items: center;
    position: absolute;
    right: 0;
    top: 0;
    height: 100%;
    width: 50%;
}

a span {
  
}

<a href="#"><span>Center</span></a>

Answer 3

a {
	background: #A9A9A9;
	display: block;
    position: absolute;
    right: 0;
    top: 0;
    height: 100%;
    width: 20%;
    vertical-align: middle;
	float: right;
	text-align: center;
}

a span {
    position: absolute;
    margin: auto;
    left: 0;
    right: 0;
    top: 50%;
    bottom: 0;
    height: 16px;
    margin-top: -8px; /* height/2 */ 
}

<a href="#"><span>Center</span></a>

Answer 4

风格的变化可能对你有帮助

 a {
    background: #A9A9A9;
    display: table;
    position: absolute;
    right: 0;
    top: 0;
    height: 100%;
    width: 20%;
    vertical-align: middle;
    float: right;
    text-align: center;
}

a span {
    display: table-cell;
    vertical-align: middle;
}

<a href="#"><span>Center</span></a>