//获取样式表样式
function getStyle(elem, styleName)
{
if(elem.currentStyle)
{
//console.log(elem.currentStyle);
return elem.currentStyle[styleName];
}
else if(window.getComputedStyle)
{
//console.log(document.defaultView.getComputedStyle(elem, null));
return document.defaultView.getComputedStyle(elem, null)[styleName];
}
return null;
}