#main_menu {
    position: relative;
}

#main_menu button {
    font-family: Lato;
    font-size: 13pt;
    width: 450px;
    height: 250px;
    text-align: center;
    margin-right: 10px;
    vertical-align: top;
    border: none;
    color: black;
    cursor: pointer;
}

#popup {
    display: none;
    width: 90%;
    height: 90%;
    padding: 10px;
    border: 2px grey solid;
    position: absolute;
    margin-left: 2%;
    top: 0;
    left: 0;
    background-color: white;
}

.HUB_buttons {
    width: 100%;
    position: relative;
    text-align: center;
}

.HUB_buttons button {
    height: 50px;
}

#popup a {  
    display:block;
    text-align: center;
    text-decoration: none;
    color: black;
    border: 1px solid black;
    padding: 10px;
    margin: 1px;
    width: 24%;
}