<div class="container">
 
         <div class="vert">
 
          <h1>Hi, I'm Nested &<span>Vertically Aligned</span></h1>
 
          <p>Abigo sudo mara paulatim odio, accumsan luptatum nibh nibh refero metuo opes ut fatua. Acsi et fere similis <strong>Using</strong> augue <strong>absolute</strong> validus. Regula <strong>positioning</strong> eu jus vel, indoles fere iaceo ea similis. Velit praemitto nulla vel luctus secundum. </p>
 
         </div>
 
</div>

这时候，就必须在定义父级元素的CSS代码中加入position: relative;才能够使内部元素垂直居中于父级内部，代码如下：

.container {
 
        position: relative;
 
        height: 500px;
 
        width: 800px;
 
        border: 10px solid #999;
 
        background: #000;
 
        margin: 20px;
 
}