你可以尝试非常简单的代码:

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

.box { 身高:90 px; 宽度:90 px; 背景:绿色; 显示:flex; 对齐项目:中心; justify-content:中心; ｝ < div class = "盒子" > Lorem < / div >

代码依赖链接:http://codepen.io/santoshkhalse/pen/xRmZwr

你可以尝试非常简单的代码:

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

.box { 身高:90 px; 宽度:90 px; 背景:绿色; 显示:flex; 对齐项目:中心; justify-content:中心; ｝ < div class = "盒子" > Lorem < / div >

代码依赖链接:http://codepen.io/santoshkhalse/pen/xRmZwr

你可以在父div中使用flex属性，并将margin:auto属性添加到子条目中:

.parent {
    display: flex;
    /* You can change this to `row` if you want the items side by side instead of stacked */
    flex-direction: column;
}

/* Change the `p` tag to what your items child items are */
.parent p {
    margin: auto;
}

你可以在这里看到更多flex的选项:https://css-tricks.com/snippets/css/a-guide-to-flexbox/

2020年的方式

.parent{ 
  display: grid;
  place-items: center;
}

<div class="small-container">
    <span>Text centered</span>
</div>

<style>
.small-container {
    width:250px;
    height:250px;
    border:1px green solid;
    text-align:center;
    position: absolute;
    top: 50%;
    left: 50%;
    -moz-transform: translateX(-50%) translateY(-50%);
    -webkit-transform: translateX(-50%) translateY(-50%);
    transform: translateX(-50%) translateY(-50%);
}
.small-container span{
    position: absolute;
    top: 50%;
    left: 50%;
    -moz-transform: translateX(-50%) translateY(-50%);
    -webkit-transform: translateX(-50%) translateY(-50%);
    transform: translateX(-50%) translateY(-50%);
}
</style>

调整线高度以获得垂直对齐。

line-height: 90px;