css保持浮層水平垂直居中的四種方法

<div class="parents">
    <div class="children"></div>
</div>

以以上代碼爲例：

   1，flex方法

.parent{
            display:flex;
            justify-content: center;
            align-items: center;
            background-color: #eee;
            width: 100%;
            height: 100%;
        }
        .parent .children{
            background-color: #751;
            width: 200px;
            height: 200px;
        }

2,利用絕對定位與transform

.parent{
            position: absolute;
            background-color: #eee;
            width: 100%;
            height: 100%;
        }
        .parent .children{
            background-color: #751;
            width: 200px;
            height: 200px;
            position: absolute;
            top: 50%;
            left: 50%;
            -webkit-transform: translate(-50%,-50%);
        }

3,將父元素定位，子元素絕對定位，利用margin負值爲子元素寬高一半來實現

.parent{
            position: relative;
            background-color: #eee;
            height: 600px;
            width: 100%;
        }
        .parent .children{
            background-color: #751;
            width: 200px;
            height: 200px;
            position: absolute;
            top: 50%;
            left: 50%;
            margin: -100px 0 0 -100px;
        }

4利用定位與margin：auto

.parent{
            width: 100%;
            height: 37.5rem/* 600px */;
            background: #09c;
            position: relative;
        }
        .children{
            width: 100px;
            height: 100px;
            background-color: #eee;
            position: absolute;
            top: 0;
            left: 0;
            bottom: 0;
            right: 0;
            margin: auto;
        }

5使用 display:table-cell 方法

.parents {
    display:table-cell;
    text-align:center;
    vertical-align:middle;
    .children:\ {
        display:inline-block;
        vertical-align:middle;
    }

}