css水平居中和垂直居中

水平居中：
内联元素：text-align:center;相对于父级居中显示
块级元素：margin:0 auto;但是需要同时width，否则无法看到效果
多个块级元素居中：在此想要探讨一下display:inline-block;和display:flex;
方法1：在父级上设置text-align:center;在元素上设置:display:inline-block;同时为了使文字向左显示，设置了text-align:left;在浏览器中的显示为，子元素高度自适应，底部对齐。
方法2：在子元素上设置display:center;justify-content:center;子元素的高度一致，与元素中内容最多的高度相同。
二种方法在谷歌，火狐，360均兼容，但是第2种方法在IE10中不兼容，之前的IE版本可想也是不兼容的。当然在此也要处理由于浮动导致离层，父级背景颜色加不上去的问题。

 <main class="inline-block-center">
   <div>
     I'm an element that is block-like with my siblings and we're centered in a row.
   </div>
   <div>
     I'm an element that is block-like with my siblings and we're centered in a row. I have more content in me than my siblings do.
   </div>
   <div>
     I'm an element that is block-like with my siblings and we're centered in a row.
   </div>
 </main>

 <main class="flex-center">
   <div>
     I'm an element that is block-like with my siblings and we're centered in a row.
   </div>
   <div>
     I'm an element that is block-like with my siblings and we're centered in a row. I have more content in me than my siblings do.
   </div>
   <div>
     I'm an element that is block-like with my siblings and we're centered in a row.
   </div>
 </main>

 body {
   background: #f06d06;
   font-size: 80%;
 }
 main {
   background: white;
   margin: 20px 0;
   padding: 10px;
 }
 main div {
   background: black;
   color: white;
   padding: 15px;
   max-width: 125px;
   margin: 5px;
 }
 .inline-block-center {
   text-align: center;
 }
 .inline-block-center div {
   display: inline-block;
   text-align: left;
 }
 .flex-center {
   display: flex;
   justify-content: center;
 }

垂直居中：

方法1：设置padding-top和padding-bottom的值相等
方法2：设置height和line-height的值相等
方法3：固定高度可以有一种处理方式position:absolute;top:50%;height:100px;margin-top:-50px;如果高度不固定，也可以使用js动态获取高度来。
还有css3的一些属性，考虑到兼容性问题不在叙述。