body{font-family:Arial,sans-serif;margin:0;padding:0;text-align:center}
main{padding:20px}
input{width:80%;padding:10px;margin:10px 0}
button{padding:10px 20px}
.error{color:red}
.btn{display:inline-block;padding:12px 20px;background:#28a745;color:#fff;text-decoration:none;border-radius:4px;margin:10px}