header{margin-bottom:1rem}header nav ul{display:flex;list-style:none;margin:0;padding:0}header nav ul li{flex:1;text-align:center}footer{margin-top:1rem;text-align:center}body{color:#222;font-family:sans-serif;line-height:1.5;margin:1rem}header,main,footer{margin:0 auto;max-width:768px}a{color:#00e;text-decoration:none}