通过JS修改标签title属性设置鼠标悬浮提示字段效果，火狐，IE8，IE9，360那什么内核 完美兼容。

var qTipTag = "*"; //所要改变的标签（需小写）!//
var qTipX = 10;    //弹出窗口位于鼠标左侧的距离。//
var qTipY = 15;    //弹出窗口位于鼠标下方的距离。//

tooltip = {
    name: "qTip",
    offsetX: qTipX,
    offsetY: qTipY,
    tip: null
}

tooltip.init = function () {
    var tipNameSpaceURI = "http://www.w3.org/1999/xhtml";
    if (!tipContainerID) { var tipContainerID = this.name; }
    var tipContainer = document.getElementById(tipContainerID);
    if (!tipContainer) {
        tipContainer = document.createElementNS ? document.createElementNS(tipNameSpaceURI, "div") : document.createElement("div");
        tipContainer.setAttribute("id", tipContainerID);
        tipContainer.setAttribute("style", "");
        tipContainer.style.display = "none";
        document.getElementsByTagName("body").item(0).appendChild(tipContainer);
    }

    if (!document.getElementById) return;
    this.tip = document.getElementById(this.name);
    if (this.tip) document.onmouseover = function (evt) { tooltip.setToolTip(evt) };
    if (this.tip) document.onmousemove = function (evt) { tooltip.move(evt) };
}

tooltip.setToolTip = function (evt) {
    anchors = document.getElementsByTagName(qTipTag);
    var obj, sTitle;

    for (var i = 0; i < anchors.length; i++) {
        obj = anchors[i];
        sAlt = obj.alt;
        sTitle = obj.title;

        if (sAlt) {
            obj.setAttribute("tiptitle", sAlt);
            obj.alt = "";
            obj.onmouseover = function () { tooltip.show(this.getAttribute('tiptitle')), tooltip.move(evt) };
            obj.onmouseout = function () { tooltip.hide() };
        }
        else if (sTitle) {
            obj.setAttribute("tiptitle", sTitle);
            obj.title = "";
            obj.onmouseover = function () { tooltip.show(this.getAttribute('tiptitle')), tooltip.move(evt) };
            obj.onmouseout = function () { tooltip.hide() };
        }
    }
}

tooltip.move = function (evt) {
    var x = 0, y = 0;
    var bodyW = document.body.clientWidth;
    var bodyH = document.body.clientHeight;
    var elementH = document.documentElement.clientHeight; //可见区域高度
    var scrollTop = (document.documentElement && document.documentElement.scrollTop) ? document.documentElement.scrollTop : document.body.scrollTop; //网页被卷去的高
    var tipW = this.tip.clientWidth;
    var tipH = this.tip.clientHeight;

    if (document.all) {//IE
        x = (document.documentElement && document.documentElement.scrollLeft) ? document.documentElement.scrollLeft : document.body.scrollLeft;
        y = (document.documentElement && document.documentElement.scrollTop) ? document.documentElement.scrollTop : document.body.scrollTop;
        x += window.event.clientX;
        y += window.event.clientY;
    }
    else {//其他浏览器
        x = evt.pageX;
        y = evt.pageY;
    }

    if (x > bodyW - tipW - this.offsetX) {
        x = x - tipW - this.offsetX;
    }
    else {
        x = x + this.offsetX;
    }
    if (y >= elementH + scrollTop - tipH - this.offsetY) {
        y = elementH + scrollTop - tipH - 2;
    }
    else {
        y = y + this.offsetY;
    }

    this.tip.style.left = x + "px";
    this.tip.style.top = y + "px";
}

tooltip.show = function (text) {
    if (!this.tip) return;

    text = text.replace(/\n/g, "<br>").replace(/\0x13/g, "<br>").replace(/\{(.[^\{]*)\}/ig, "");
    var strTab =
        "<table id='toolTipTalbe' style='border:1px solid #007db5;line-height:140%;border-collapse: collapse;'>" +
        "   <tr>" +
        "       <td style='background-color:#99CC33;padding:8px;text-align:center;'>" +
        "           <span style='font-size: 16pt; font-family: 隶书;font-weight: 200;'>--项目提示--</span>" +
        "       </td>" +
        "   </tr>" +
        "   <tr><td style='background-color:#EDEDED;padding:8px;'>" + text + "</td></tr>" +
        "</table>";
    this.tip.innerHTML = strTab;
    this.tip.style.cssText = "display:block;position:absolute;z-index:10001;";
    if (this.tip.clientWidth >= document.documentElement.clientWidth / 3) {
        this.tip.style.width = document.documentElement.clientWidth / 3 + "px";
    }
}

tooltip.hide = function () {
    if (!this.tip) return;
    this.tip.innerHTML = "";
    this.tip.style.display = "none";
}

window.onload = function () {
    tooltip.init();
}

　　将以上代码保存为JS文件引入到页面中    设置标签title属性 

例：<a href="#" title="我是提示内容。。。哈哈<br/>还可以换行呀。。。哈哈。">需要提示的标签</a>      

OK。样式可以通过修改DIV中的表格自定义

效果：

 

以上代码是网上找资料等 修改而来 目前网上有好几个例子 但是对IE9 火狐等都没有兼容。