<div class="div1">
    <div class="div2">自适应浏览器水平垂直居中</div>
</div>

.div1{
            width: auto;
            height: 600px;
            background: #cccccc;
            position: relative;
        }
.div2{
            position: absolute;
            left: 50%;
            top: 50%;
            margin-left: -600px;
            margin-top: -200px;
            width: 1200px;
            height: 400px;
            background: #4fcc8d;
            line-height: 400px;
            font-size: 36px;
            text-align: center;
        }