:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --bg: #f1f5f9;
  --card: #fff;
  --text: #0f172a;
  --muted: #64748b;
  --success: #10b981;
  --danger: #ef4444;
  --warning: #f59e0b;
  --border: #e2e8f0;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
body { margin: 0; min-height: 100vh; background: var(--bg); color: var(--text); font-family: "Segoe UI", system-ui, -apple-system, sans-serif; }
button, input, textarea { font: inherit; }
.container { width: 90%; max-width: 750px; margin: 25px auto; }
.card { padding: 28px; background: var(--card); border: 1px solid var(--border); border-radius: 16px; box-shadow: 0 10px 15px -3px rgb(0 0 0 / 5%); }
.btn { padding: 10px 18px; border: 0; border-radius: 8px; color: #fff; font-weight: 700; cursor: pointer; }
.btn-primary { background: var(--primary-dark); }
.btn-secondary { background: var(--muted); }
.btn-success { background: var(--success); }
.btn-danger { background: var(--danger); }
.btn-warning { background: var(--warning); }
.btn-block { width: 100%; }
.button-row { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 16px; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
.empty-state, .error-state, .unknown-state { padding: 16px; border-radius: 10px; }
.empty-state { background: #f8fafc; color: var(--muted); }
.error-state { background: #fee2e2; color: #991b1b; }
.unknown-state { background: #fef3c7; color: #92400e; }

@media (max-width: 600px) {
  .card { padding: 20px; }
  .button-row .btn { width: 100%; }
}