兼容主流浏览器的背景遮盖和居中浮动层的CSS样式
html, body{ height: 100%; margin: 0px; font-size: 12px;} .mydiv{ background: #f1f1f1; padding: 15px 30px; border: 5px solid #ccc; z-index: 99; left: 50%; /*FF IE7*/ top: 50%; /*FF IE7*/ margin-left: -150px !important; /*FF IE7 该值为本身宽的一半 */ margin-top: -60px !important; /*FF IE7 该值为本身高的一半*/ margin-top: 0px; position: fixed !important; /*FF IE7*/ position: absolute; /*IE6*/ _top: expression(eval(document.compatMode && document.compatMode=='CSS1Compat') ? documentElement.scrollTop + (document.documentElement.clientHeight-this.offsetHeight)/2 :/*IE6*/ document.body.scrollTop + (document.body.clientHeight - this.clientHeight)/2); /*IE5 IE5.5*/} .bg{ background-color: #ccc; width: 100%; height: 100%; left: 0; top: 0; /*FF IE7*/ filter: alpha(opacity=50); /*IE*/ opacity: 0.5; /*FF*/ z-index: 1; position: fixed !important; /*FF IE7*/ position: absolute; /*IE6*/ _top: expression(eval(document.compatMode && document.compatMode=='CSS1Compat') ? documentElement.scrollTop + (document.documentElement.clientHeight-this.offsetHeight)/2 :/*IE6*/ document.body.scrollTop + (document.body.clientHeight - this.clientHeight)/2); /*IE5 IE5.5*/}?