css实现字体从上到下渐变为无

html:
<p>第一章 既然回不去，那认真留下来 </p>
css:
{
background-image: -webkit-gradient(linear, 0 0, 0 bottom, from(#999999), to(#eeeeee));
-webkit-background-clip: text;
-webkit-text-fill-color: transparent;
}