.main_menu {
    font-family: "Trebuchet MS", Arial, Verdana;
    font-size: 120%;
    width: 70%;
    margin: 0 auto;
    behavior: url("/js/csshover3.htc");
}

.main_menu ul {
    padding: 0;
    margin: 0;
    height: 30px;
    text-align: center;
    z-index: 1;
}

.main_menu li {
    z-index:1;
    list-style-type: none;
    background-color: black;
    width: 150px;
    height: 100%;
    margin: 0 1px;
    padding: 0;
    float: left;
    position: relative;
}

.main_menu a {
    color: white;
    display: block;
    line-height: 30px;
    text-decoration: none;
    width: 150px;
    margin: 0;
    padding: 0;
}

.main_menu a:hover  {
    background-color: #666;
    font-weight: bold;
}

.main_menu li:hover ul {
    display: block;
}

.main_menu li:hover ul ul {
    display: none;
}

.main_menu ul ul {
    display: none;
    position: absolute;
    left: 0;
    width: 100%;
}

.main_menu ul ul li {
    display: inline;
    font-size: 12px;
}

.main_menu ul ul li a {
    float: none;
    height: 30px;
    margin: 0;
    padding: 0;
}

.main_menu ul ul li:hover ul {
    left: 145px;
    top: 0;
    position: absolute;
    display: block;
}

.main_menu ul ul li:hover ul ul {
    display: none;
}

.main_menu ul ul ul li:hover ul {
    display: block;
}