js动态创建css样式

function setCssText(css){ 
    if(document.all){ // document.createStyleSheet(url)
        window.style = css
        document.createStyleSheet("javascript:style")
    }else{ //document.createElement(style)
        var style = document.createElement('style')
        style.type = 'text/css'
        style.innerHTML = css
        document.getElementsByTagName('HEAD').item(0).appendChild(style)
    } 
}
setCssText('body { color: red }')