:root[data-theme="dark"] {
  --bg: #101318;
  --surface: #171b22;
  --surface-2: #222833;
  --text: #f8fafc;
  --muted: #9aa8ba;
  --border: #2b3340;
  --shadow: 0 18px 45px rgba(0, 0, 0, .24);
}

:root[data-theme="dark"] .topbar { background: rgba(23, 27, 34, .88); }
:root[data-theme="dark"] .sidebar { background: #0b0f16; }
:root[data-theme="dark"] .alert-danger { background: #451a1a; color: #fecaca; }