.principal.main_window{
    left : 5%;
    top: 15%;
}


.main_menu{
    position: absolute;
    top:150px;
    left: 600px;
    display: none; 
    z-index: 1;
}

.main_menu .item_menu{
    float: left;
    display: inline;
    clear: both;
    border: 1px solid #eee;
    background: #989999;
    border-radius: 5px;
    width: 300px;
    height: 80px;
    font-size: 26px;
    color: white;
    text-align: center;
    line-height: 80px;
}

.main_menu .item_menu.over{
    background: #000000;
    cursor: pointer;
    color: white;
}