body{font-family:Arial;margin:20px;background:#f5f7fb;}
.nav a{margin-right:15px;text-decoration:none;font-weight:bold;}
table{border-collapse:collapse;width:100%;background:white}
td,th{border:1px solid #ddd;padding:8px;text-align:center}
button{padding:6px 10px;background:#2d89ef;color:white;border:none}
.error{color:red}
.success{color:green}