兼容IE与firefox的css 线性渐变（linear-gradient）
IE系列
filter: progid:DXImageTransform.Microsoft.Gradient(startColorStr='#FF0000',endColorStr='#F9F900',gradientType='0');
参数：startColorStr起始颜色 endColorStr结束颜色 gradientType为0时代表垂直，为1时代表水平
Firefox
background: -moz-linear-gradient(top, #FF0000, #F9F900);
参数：top、bottom垂直，left、right水平 例如：top时从顶部由#FF0000到#F9F900渐变，bottom时从底部由#FF0000到#F9F900渐变
Opera
background: -o-linear-gradient(top,#FF0000, #F9F900);
参数：top、bottom垂直，left、right水平 例如：top时从顶部由#FF0000到#F9F900渐变，bottom时从底部由#FF0000到#F9F900渐变
webkit，如Chrome、Safari等
background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#FF0000), to(#F9F900));
参数：linear线性， x1 x2, x3 x4 x1与x3相同时垂直，x2与x4相同时水平 from起始颜色 to结束颜色
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>线性渐变（linear-gradient）---http://www.jb51.net</title>
<style type="text/css">
.test1
{
width: 200px;
height: 80px;
text-align: center;
line-height: 80px;
margin-bottom: 10px;
color: White;
font-size: 20px;
filter: progid:DXImageTransform.Microsoft.Gradient(startColorStr='#FF0000',endColorStr='#F9F900',gradientType='0');
background: -moz-linear-gradient(top, #FF0000, #F9F900);
background: -o-linear-gradient(top,#FF0000, #F9F900);
background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#FF0000), to(#F9F900));
}
.test2
{
width: 200px;
height: 80px;
text-align: center;
line-height: 80px;
margin-bottom: 10px;
color: White;
font-size: 20px;
filter: progid:DXImageTransform.Microsoft.Gradient(startColorStr='#FF0000',endColorStr='#F9F900',gradientType='1');
background: -moz-linear-gradient(left, #FF0000, #F9F900);
background: -o-linear-gradient(left,#FF0000, #F9F900);
background: -webkit-gradient(linear, 0% 0%, 100% 0%, from(#FF0000), to(#F9F900));
}
</style>
</head>
<body>
<div class="test1">
垂直渐变
</div>
<div class="test2">
水平渐变
</div>
</body>
</html>
