CSS控制图片的最大宽度

<img class="photoresize" style="border:1px solid #ccc; padding:2px; margin:10px;" src="<%=rs("img")%>" /><style type="text/css">          .photoresize { max-width:600px; myimg:expression(onload=function(){ this.style.width=(this.offsetWidth > 600)?"600px":"auto"}     ); }          </style>.neirong img{max-width:680px;myimg:expression(onload=function(){this.style.width=(this.offsetWidth > 680)?"680px":"auto"});}#upscroll li{ height:20px; line-height:20px;}