这是一个简单的例子。不知道是否符合你的需求。
body{
background:#111;
}
ul{
padding:0;
margin:0;
}
li{
margin-left:20px;
width:200px;
list-style:none;
border-bottom:dotted 2px #99f;
color:#99f;
position:relative;
}
li:before{
content:'+';
position:absolute;
left:-15px;
}
li:after{
content:'';
position:absolute;
height:2px;
width:100%;
top:100%;
background:red;
left:0;
background: -moz-linear-gradient(left, rgba(17,17,17,0) 0%, rgba(17,17,17,1) 100%); /* FF3.6+ */
background: -webkit-gradient(linear, left top, right top, color-stop(0%,rgba(17,17,17,0)), color-stop(100%,rgba(17,17,17,1))); /* Chrome,Safari4+ */
background: -webkit-linear-gradient(left, rgba(17,17,17,0) 0%,rgba(17,17,17,1) 100%); /* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(left, rgba(17,17,17,0) 0%,rgba(17,17,17,1) 100%); /* Opera 11.10+ */
background: -ms-linear-gradient(left, rgba(17,17,17,0) 0%,rgba(17,17,17,1) 100%); /* IE10+ */
background: linear-gradient(to right, rgba(17,17,17,0) 0%,rgba(17,17,17,1) 100%); /* W3C */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#00111111', endColorstr='#111111',GradientType=1 ); /* IE6-9 */
}
http://jsfiddle.net/KZPbf/
方便的跨浏览器渐变生成器:http: //www.colorzilla.com/gradient-editor/