完成渐变效果就变得非常简单，跟用PS的操作是一样一样的。  

/*你可以直接使用这个网站生成代码呢*/
background: #000; /* Old browsers */
background: -moz-radial-gradient(center, ellipse cover,  #444 0%, #000000 90%); /* FF3.6+ */
background: -webkit-gradient(radial, center center, 0px, center center, 100%, color-stop(0%,#444), color-stop(90%,#000000)); /* Chrome,Safari4+ */
background: -webkit-radial-gradient(center, ellipse cover,  #444 0%,#000000 90%); /* Chrome10+,Safari5.1+ */
background: -o-radial-gradient(center, ellipse cover,  #444 0%,#000000 90%); /* Opera 12+ */
background: -ms-radial-gradient(center, ellipse cover,  #444 0%,#000000 90%); /* IE10+ */
background: radial-gradient(ellipse at center,  #444 0%,#000000 90%); /* W3C */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#444444', endColorstr='#000000',GradientType=1 );

链接: https://fly63.com/nav/3043