_{.b{box-shadow:inset 1px -1px 0 #f1f1f1;text-shadow:1px 1px 0px #630;}}

_{filter:progid:DXImageTransform.Microsoft.gradient(enabled='true',startColorstr='#99000000',endColorstr='#99000000');background:rgba(0,0,0,.6);}

_{background:rgba(0,0,0,0.5);filter:progid:DXImageTransform.Microsoft.gradient(GradientType=0,startColorstr='#50000000',endColorstr='#50000000')\9;}

_{看哪个startColorstr和endColorstr，一共8位，后6位是RGB的颜色代码，前两位是16进制的}

_{比如60%透明，就是256x0.6=154，再换算成16进制=9A
background-image:-ms-linear-gradient(top, #fff, #ddd); ie10渐变
http://www.iefans.net/ie10-yulanban-css3-jianbian/} 

_{alpha透明兼容代码生成：}

_{http://leegorous.net/tools/bg-alpha.html}

_{16进制的转换}

_{http://www.zhangxinxu.com/wordpress/2010/05/rgba%E9%A2%9C%E8%89%B2%E4%B8%8E%E5%85%BC%E5%AE%B9%E6%80%A7%E7%9A%84%E5%8D%8A%E9%80%8F%E6%98%8E%E8%83%8C%E6%99%AF%E8%89%B2/}

_透明兼容