ul.main_menu {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: antiquewhite;
}
ul.main_menu li {
    float:left;
}
ul.main_menu li a {
    display: block;
    color:navy;
    text-align: center;
    padding: 24px , 26px;
    text-decoration: none;
}

ul.main_menu li a:hover {
    background-color: brown;
    color: antiquewhite;
}