Simple implementation case of floating left and right sliding effect of page pictures_javascript skills

.box ul {
 margin: 0px;
 padding: 0px;
 float: left;
 list-style-type: none;
}

.box li {
 width: 150px;
 height: 100px;
 float: left;
 cursor: pointer;
 display: inline;
 margin: 0 10px 10px 0;
 border: 5px solid #333;
}

#bg {
 width: 100%;
 height: 898px;
 position: absolute;
 left: 0px;
 top: 0px;
 background: #000;
 filter: alpha(opacity : 50);
 opacity: 0.5;
 display: none;
}

#bg1 {
 width: 100%;
 height: 100%;
 position: absolute;
 left: 0px;
 top: 0px;
 background: #000;
 filter: alpha(opacity : 50);
 opacity: 0.5;
 display: none;
}
#bottom {
 width: 215px;
 height: 50px;
 position: absolute;
 left: 50%;
 bottom: 0px;
 margin: 0 0 0 -107px;
 border: 1px solid #232323;
 background: #444;
 padding: 1px;
 z-index: 1;
 display: none;
}

#bottom ul {
 width: 100%;
 height: 100%;
 margin: 0px;
 padding: 0px;
 list-style-type: none;
 background: #000;
}

#bottom li {
 background: url(../images/ico.jpg) no-repeat;
 float: left;
 display: inline;
 margin: 8px 0 0 18px;
 cursor: pointer;
}

#bottom li.prev {
 width: 30px;
 height: 33px;
 background-position: 0 0;
}

#bottom li.next {
 width: 30px;
 height: 33px;
 background-position: -35px 0;
}

#bottom li.img {
 width: 30px;
 height: 33px;
 background-position: -106px 0;
}

#bottom li.close {
 width: 31px;
 height: 33px;
 background-position: -70px 0;
}

#frame {
 background: #fff;
 padding: 3px;
 position: absolute;
 z-index: 2;
 display: none;
 filter: alpha(opacity : 0);
 opacity: 0;
 text-align: center;
}

#bottom1 {
 width: 215px;
 height: 50px;
 position: absolute;
 left: 50%;
 bottom: 0px;
 margin: 0 0 0 -107px;
 border: 1px solid #232323;
 background: #444;
 padding: 1px;
 z-index: 1;
 display: none;
}

#bottom1 ul {
 width: 100%;
 height: 100%;
 margin: 0px;
 padding: 0px;
 list-style-type: none;
 background: #000;
}

#bottom1 li {
 background: url(../../images/ico.jpg) no-repeat;
 float: left;
 display: inline;
 margin: 8px 0 0 18px;
 cursor: pointer;
}

#bottom1 li.prev {
 width: 30px;
 height: 33px;
 background-position: 0 0;
}

#bottom1 li.next {
 width: 30px;
 height: 33px;
 background-position: -35px 0;
}

#bottom1 li.img {
 width: 30px;
 height: 33px;
 background-position: -106px 0;
}

#bottom1 li.close {
 width: 31px;
 height: 33px;
 background-position: -70px 0;
}

#frame1 {
 background: #fff;
 padding: 3px;
 position: absolute;
 z-index: 2;
 display: none;
 filter: alpha(opacity : 0);
 opacity: 0;
 text-align: center;
}
/
html,body {
 height: 100%;
 margin: 0px;
 font-size: 12px;
}

.mydiv {
 background-color: #FFCC66;
 background:url(../images/loginbg.png) no-repeat;
 border: 0px solid #f00;
 overflow-y:auto;
 overflow-x:auto;
 text-align: center;
 line-height: 40px;
 font-size: 12px;
 font-weight: bold;
 z-index: 999;
 width: 434px;
 height: 238px;
 left: 50%;
 top: 50%;
 margin-left: -200px !important; /*FF IE7 该值为本身宽的一半 */
 margin-top: -80px !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*/
}
.mydiv1 {
 background-color: #FFCC66;
 border: 0px solid #f00;
 text-align: center;
 line-height: 40px;
 font-size: 12px;
 font-weight: bold;
 overflow-y:auto;
 overflow-x:auto;
 z-index: 999;
 width: 434px;
 height: 238px;
 left: 50%;
 top: 50%;
 margin-left: -200px !important; /*FF IE7 该值为本身宽的一半 */
 margin-top: -80px !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,.popIframe {
 background-color: #666;
 display: none;
 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 );
}

.popIframe {
 filter: alpha(opacity = 0); /*IE*/
 opacity: 0; /*FF*/
}