十年挑戰之水平垂直置中

<div class="container">
	<div class="child">
		2008<br/>
		絕對定位
	</div>
</div>

.container {
  width: 300px;
  height: 300px;
  background: white;
  border: 1px solid black;

  position: relative;

  .child {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    text-align: center;
    width: 100%;
  }
}

.container {
  width: 300px;
  height: 300px;
  background: black;

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

  .child {
    margin: auto;
    color: white;
  }
}