body {margin: 2em; background-color:#000; color:#6c3;}
a:link {color:#0f0;}
a:visited,a:active {color:#090;}
a:hover {color:#9f9;}

#logo {text-align:center;}
#logo h1 {margin:0;padding:0;}

.center {text-align:center;}

#menu {text-align: center; white-space: nowrap;font-family: arial,geneva,sans-serif;
	font-size: smaller;display:flex;flex-wrap:wrap;justify-content:space-around;}

#menu > div,#menu > div > div  {display:flex;flex-wrap:wrap;justify-content:center;}
#menu > div {border:thin solid red;}
#menu > div > div {border:thin solid yellow;}