@media (max-width: 899px) {
  .main-layout {
    flex-direction: column;
  }
}

@media (max-width: 899px) {
  .sidebar-nav {
    width: 100% !important;
    min-width: 100% !important;
    height: auto !important;
    position: sticky !important;
    top: 0;
    z-index: 1001;
    border-right: none !important;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    background: #0f172a; /* 移动端使用纯色背景避免渐变导致的文字不清晰 */
  }
  
  .nav-header {
    height: 60px !important;
    padding: 0 16px !important;
  }
  
  .nav-section {
    display: none; /* 移动端默认隐藏菜单，可以后续添加点击展开逻辑 */
  }
  
  .sidebar-footer {
    padding: 8px 16px !important;
    flex-direction: row !important;
    justify-content: space-between !important;
    align-items: center !important;
  }
  
  .sidebar-footer .lang-selector,
  .sidebar-footer .theme-btn {
    width: auto !important;
  }

  .sidebar-toggle.side-toggle {
    display: none !important;
  }

  /* 移动端菜单展开状态 */
  .sidebar-nav.mobile-open .nav-section {
    display: block !important;
    max-height: calc(100vh - 60px);
    overflow-y: auto;
    background: #0f172a;
    padding: 16px;
    animation: slideDown 0.3s ease-out;
  }

  @keyframes slideDown {
    from { transform: translateY(-10px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
  }

  .mobile-menu-toggle {
    display: flex !important;
    flex-direction: column;
    justify-content: space-between;
    width: 24px;
    height: 18px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0;
    z-index: 1001;
  }

  .mobile-menu-toggle span {
    width: 100%;
    height: 2px;
    background-color: #e5e7eb;
    border-radius: 2px;
    transition: all 0.3s ease;
  }

  .sidebar-nav.mobile-open .mobile-menu-toggle span:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
  }

  .sidebar-nav.mobile-open .mobile-menu-toggle span:nth-child(2) {
    opacity: 0;
  }

  .sidebar-nav.mobile-open .mobile-menu-toggle span:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
  }
}