用CSS更改圆角按钮的颜色

先谢谢你!

我能用CSS做一个圆角按钮。我喜欢鼠标悬停在按钮上,整个按钮都会改变颜色,而不仅仅是最内部的部分。请帮忙!

我的假设是IAM应该有一些onMouseOver为“”的javascript,对吗?

页面如下: http://biozenconsulting.com/new/

(同样,当在IE8和Chrome中查看时,如何清除出现在右角的小方框?)

这是HTML代码:

<div class="nav_menu" onclick="location.href='index.htm'">
    <b class="top_menu"><b class="top_menu1"><b></b></b><b class="top_menu2"><b></b></b><b class="top_menu3"></b><b class="top_menu4"></b><b class="top_menu5"></b></b>
    <div class="top_menufg">
        <!-- content goes here -->
        Home
    </div>
    <b class="top_menu"><b class="top_menu5"></b><b class="top_menu4"></b><b class="top_menu3"></b><b class="top_menu2"><b></b></b><b class="top_menu1"><b></b></b></b>
</div>

这是CSS:

.nav_menu {
    text-align: center;
    color: #353535;
    font-size: 20pt;
    font-family: Verdana, Geneva, sans-serif;
    float: left;
    width: 33%;
}

#about {
    margin: 0 .5% 0 .5%;
}

<!-- For rounded boxes -->
.top_menu {
    display:block
    overflow: hidden;
}
.top_menu *{
    display:block;
    height:1px;
    overflow:hidden;
    font-size:.01em;
    background:#AAAAAA
}

.top_menu1{
    margin-left:3px;
    margin-right:3px;
    padding-left:1px;
    padding-right:1px;
    border-left:1px solid #AAAAAA;
    border-right:1px solid #AAAAAA;
    background:#AAAAAA
}
.top_menu2{
    margin-left:1px;
    margin-right:1px;
    padding-right:1px;
    padding-left:1px;
    border-left:1px solid #AAAAAA;
    border-right:1px solid #AAAAAA;
    background:#AAAAAA
}
.top_menu3{
    margin-left:1px;
    margin-right:1px;
    border-left:1px solid #AAAAAA;
    border-right:1px solid #AAAAAA;
}
.top_menu4{
    border-left:1px solid #AAAAAA;
    border-right:1px solid #AAAAAA
}
.top_menu5{
    border-left:1px solid #AAAAAA;
    border-right:1px solid #AAAAAA
}
.top_menufg{
    background:#AAAAAA
}
.top_menufg:hover{
    background-color: #888888;
    cursor: pointer;
}
<!-- For rounded boxes -->