body{font-family:Arial;margin:0}header{background:#2e7d32;color:#fff;padding:50px;text-align:center}.btn{background:#fff;color:#2e7d32;padding:10px 18px;text-decoration:none}nav{padding:15px;background:#f3f3f3}nav a{margin-right:15px}main{padding:20px}footer{padding:20px;background:#222;color:#fff;text-align:center}