* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, sans-serif;
  background: #f5f5f7;
  color: #1a1a1a;
}
.container { max-width: 900px; margin: 0 auto; padding: 16px; }
.topnav {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  padding: 12px 16px;
  background: #1a1a2e;
}
.topnav a, .topnav button {
  color: #fff;
  text-decoration: none;
  background: none;
  border: none;
  font-size: 1rem;
  cursor: pointer;
}
.logout-form { margin-left: auto; }
.login-form { max-width: 320px; margin: 48px auto; display: flex; flex-direction: column; gap: 12px; }
.error { color: #b00020; }
table { width: 100%; border-collapse: collapse; }
th, td { text-align: left; padding: 8px; border-bottom: 1px solid #ddd; }
@media (max-width: 480px) {
  table, thead, tbody, th, td, tr { display: block; }
  th { display: none; }
  td { border: none; padding: 4px 0; }
  tr { border-bottom: 1px solid #ddd; padding: 8px 0; }
}