CSS自定义弹出框

<script type="text/javascript" language="javascript"> 
function sAlert(str){ 
var msgw,msgh,bordercolor; 
msgw=400;//提示窗口的宽度 
msgh=100;//提示窗口的高度 
titleheight=25//提示窗口标题高度 
bordercolor="#336699";//提示窗口的边框颜色 
titlecolor="#99CCFF";//提示窗口的标题颜色 
var sWidth,sHeight; 
sWidth=document.body.offsetWidth;//浏览器工作区域内页面宽度 或使用 screen.width//屏幕的宽度 
sHeight=screen.height;//屏幕高度（垂直分辨率） 
//背景层（大小与窗口有效区域相同，即当弹出对话框时，背景显示为放射状透明灰色） 
var bgObj=document.createElement("div");//创建一个div对象（背景层） //动态创建元素，这里创建的是 div 
//定义div属性，即相当于(相当于，但确不是，必须对对象属性进行定义 
//<div id="bgDiv" style="position:absolute; top:0; background-color:#777; filter:progid:DXImagesTransform.Microsoft.Alpha(style=3,opacity=25,finishOpacity=75); opacity:0.6; left:0; width:918px; height:768px; z-index:10000;"></div> 
bgObj.setAttribute('id','bgDiv'); 
bgObj.style.position="absolute"; 
bgObj.style.top="0"; 
bgObj.style.background="#777"; 
bgObj.style.filter="progid:DXImageTransform.Microsoft.Alpha(style=3,opacity=25,finishOpacity=75"; 
bgObj.style.opacity="0.6"; 
bgObj.style.left="0"; 
bgObj.style.width=sWidth + "px"; 
bgObj.style.height=sHeight + "px"; 
bgObj.style.zIndex = "10000"; 
document.body.appendChild(bgObj);//在body内添加该div对象 
//创建一个div对象（提示框层） 
var msgObj=document.createElement("div") 
//定义div属性，即相当于 
//<div id="msgDiv" align="center" style="background-color:white; border:1px solid #336699; position:absolute; left:50%; top:50%; font:12px/1.6em Verdana,Geneva,Arial,Helvetica,sans-serif; margin-left:-225px; margin-top:npx; width:400px; height:100px; text-align:center; line-height:25px; z-index:100001;"></div> 
msgObj.setAttribute("id","msgDiv"); 
msgObj.setAttribute("align","center"); 
msgObj.style.background="white"; 
msgObj.style.border="1px solid " + bordercolor; 
msgObj.style.position = "absolute"; 
msgObj.style.left = "50%"; 
msgObj.style.top = "50%"; 
msgObj.style.font="12px/1.6em Verdana, Geneva, Arial, Helvetica, sans-serif"; 
msgObj.style.marginLeft = "-225px" ; 
msgObj.style.marginTop = -75+document.documentElement.scrollTop+"px"; 
msgObj.style.width = msgw + "px"; 
msgObj.style.height =msgh + "px"; 
msgObj.style.textAlign = "center"; 
msgObj.style.lineHeight ="25px"; 
msgObj.style.zIndex = "10001"; 
var title=document.createElement("h4");//创建一个h4对象（提示框标题栏） 
//定义h4的属性，即相当于 
//<h4 id="msgTitle" align="right" style="margin:0; padding:3px; background-color:#336699; filter:progid:DXImageTransform.Microsoft.Alpha(startX=20, startY=20, finishX=100, finishY=100,style=1,opacity=75,finishOpacity=100); opacity:0.75; border:1px solid #336699; height:18px; font:12px Verdana,Geneva,Arial,Helvetica,sans-serif; color:white; cursor:pointer;" onclick="">关闭</h4> 
title.setAttribute("id","msgTitle"); 
title.setAttribute("align","right"); 
title.style.margin="0"; 
title.style.padding="3px"; 
title.style.background=bordercolor; 
title.style.filter="progid:DXImageTransform.Microsoft.Alpha(startX=20, startY=20, finishX=100, finishY=100,style=1,opacity=75,finishOpacity=100);"; 
title.style.opacity="0.75"; 
title.style.border="1px solid " + bordercolor; 
title.style.height="18px"; 
title.style.font="12px Verdana, Geneva, Arial, Helvetica, sans-serif"; 
title.style.color="white"; 
title.style.cursor="pointer"; 
title.innerHTML="关闭"; 
title.onclick=removeObj; 
var button=document.createElement("input");//创建一个input对象（提示框按钮） 
//定义input的属性，即相当于 
//<input type="button" align="center" style="width:100px; align:center; margin-left:250px; margin-bottom:10px;" value="关闭"> 
button.setAttribute("type","button"); 
button.setAttribute("value","关闭"); 
button.style.width="60px"; 
button.style.align="center"; 
button.style.marginLeft="250px"; 
button.style.marginBottom="10px"; 
button.style.background=bordercolor; 
button.style.border="1px solid "+ bordercolor; 
button.style.color="white"; 
button.onclick=removeObj; 
function removeObj(){//点击标题栏触发的事件 
   document.body.removeChild(bgObj);//删除背景层Div 
   document.getElementById("msgDiv").removeChild(title);//删除提示框的标题栏 
   document.body.removeChild(msgObj);//删除提示框层 
} 
document.body.appendChild(msgObj);//在body内添加提示框div对象msgObj 
document.getElementById("msgDiv").appendChild(title);//在提示框div中添加标题栏对象title 
var txt=document.createElement("p");//创建一个p对象（提示框提示信息） 
//定义p的属性，即相当于 
//<p style="margin:1em 0;" id="msgTxt">测试效果</p> 
txt.style.margin="1em 0" 
txt.setAttribute("id","msgTxt"); 
txt.innerHTML=str;//来源于函数调用时的参数值 
document.getElementById("msgDiv").appendChild(txt);//在提示框div中添加提示信息对象txt 
document.getElementById("msgDiv").appendChild(button);//在提示框div中添加按钮对象button 
} 
</script>