css样式兼容性写法和处理。

一、 css3渐变属性linear-gradient

css3背景颜色渐变属性的兼容性写法。
一般情况下，css3背景渐变考虑兼容性的写法如下：

.classname{
    background: -moz-linear-gradient(top, #000000 0%, #ffffff 100%);
    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#000000), color-stop(100%,#ffffff));
    background: -webkit-linear-gradient(top, #000000 0%,#ffffff 100%);
    background: -o-linear-gradient(top, #000000 0%,#ffffff 100%);
    background: -ms-linear-gradient(top, #000000 0%,#ffffff 100%);
    background: linear-gradient(to bottom, #000000 0%,#ffffff 100%);
}

但是ie6-9不兼容linear-gradient，需要使用ie下的私有属性filter，所以代码如下：

.classname{
    background: #000000;
    background: -moz-linear-gradient(top,  #000000 0%, #ffffff 100%);
    background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#000000), color-stop(100%,#ffffff));
    background: -webkit-linear-gradient(top,  #000000 0%,#ffffff 100%);
    background: -o-linear-gradient(top,  #000000 0%,#ffffff 100%);
    background: -ms-linear-gradient(top,  #000000 0%,#ffffff 100%);
    background: linear-gradient(to bottom,  #000000 0%,#ffffff 100%);
    filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#000000', endColorstr='#ffffff',GradientType=0 );
}
:root .classname{filter:none;}