body {
    margin: 0;
  }

  .top-menu {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: #333;
    padding: 10px 20px;
  }

  .top-menu img.logo {
    height: 40px;
  }

  .menu-links a {
    color: white;
    text-decoration: none;
    margin-left: 20px;
    font-size: 16px;
  }

  .menu-links a:hover {
    text-decoration: underline;
  }

  .item {
    margin-bottom: 20px;
    background: #fff;
    border: 1px solid #ccc;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  }

  .item-header {
    padding: 15px;
    background: #e0e0e0;
    border-bottom: 1px solid #ccc;
    user-select: none;
    cursor: pointer;
  }

  .subitems {
    padding: 15px;
    display: none;
    grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    gap: 10px;
  }

  .subitems.show {
    display: flex;
  }

  .subitems button {
    padding: 10px;
    font-size: 0.9em;
    cursor: pointer;
    border: 1px solid #999;
    border-radius: 5px;
    background: #e6f0ff;
    transition: background 0.3s;
  }

  .subitems button:hover {
    background: #d0e5ff;
  }