.logo {float:left;}
.top {
    display: flex;
    flex-direction: column;}
#nav > .mainlevel {
    float: left;
    width: 103px;
    height: 37px;
    position: relative;
    z-index: 1000;
    display: block;}
.menu_on {
color:#333; font-size:16px; 
font-weight:bold;}