alert弹出窗口的好看点得样式

 function sAlert(str) {
        var msgw, msgh, bordercolor;
        msgw = 200; //提示窗口的宽度
        msgh = 100; //提示窗口的高度
        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;
        sHeight = document.body.offsetHeight;

        var bgObj = document.createElement("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";
        document.body.appendChild(bgObj);
        var msgObj = document.createElement("div")
        msgObj.setAttribute("id", "msgDiv");
        msgObj.setAttribute("align", "center");
        msgObj.style.position = "absolute";
        msgObj.style.background = "white";
        msgObj.style.font = "12px/1.6em Verdana, Geneva, Arial, Helvetica, sans-serif";
        msgObj.style.border = "1px solid " + bordercolor;
        msgObj.style.width = msgw + "px";
        msgObj.style.height = msgh + "px";
        msgObj.style.top = (document.documentElement.scrollTop + (sHeight - msgh) / 2) + "px";
        msgObj.style.left = (sWidth - msgw) / 2 + "px";
        var title = document.createElement("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 = function() {
            document.body.removeChild(bgObj);
            document.getElementById("msgDiv").removeChild(title);
            document.body.removeChild(msgObj);
        }
        document.body.appendChild(msgObj);
        document.getElementById("msgDiv").appendChild(title);
        var txt = document.createElement("p");
        txt.style.margin = "1em 0"
        txt.setAttribute("id", "msgTxt");
        txt.innerHTML = str;
        document.getElementById("msgDiv").appendChild(txt);
    }