.sidebar-center {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background-color: #f4f4f4;
  padding: 2rem 1.5rem;
  border-radius: 12px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
  z-index: 1000;
}

.submenu {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  align-items: center;
}

.submenu a {
  text-decoration: none;
  color: #333;
  font-weight: 500;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  transition: background 0.2s;
  white-space: nowrap;
}

.submenu a:hover {
  background-color: #e0e0e0;
}