.nav_hover {
    color: #fff;
    text-shadow: 0 0 5px #fff, 0 0 10px #fff, 0 0 15px #fff, 0 0 20px #ff00ff, 0 0 30px #ff00ff, 0 0 40px #ff00ff, 0 0 55px #ff00ff, 0 0 75px #ff00ff;
}

.yuandian {
    background:url(images/dot_off.png) no-repeat center;
    width:80px;
    height:60px;
    display:inline-block;
}
.yuandian:hover {
    background: url(images/dot_on.png) no-repeat center;
}