.mobile-menu-btn {
  display: none;
}

.sidebar-backdrop {
  display: none;
}

body.sidebar-scroll-lock {
  overflow: hidden;
}

@media (max-width: 768px) {
  :root {
    --sidebar-drawer-width: min(88vw, 300px);
  }

  body {
    height: 100dvh;
  }

  .app {
    height: 100dvh;
  }

  .sidebar-backdrop {
    display: block;
    position: fixed;
    inset: 0;
    z-index: 350;
    border: none;
    padding: 0;
    margin: 0;
    background: rgba(0, 0, 0, 0.55);
    cursor: pointer;
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition:
      opacity var(--motion-duration-sidebar, 0.28s) var(--motion-ease-standard, cubic-bezier(0.4, 0, 0.2, 1)),
      visibility var(--motion-duration-sidebar, 0.28s);
  }

  .sidebar-backdrop.is-open {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
  }

  .sidebar-region {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: var(--sidebar-drawer-width);
    z-index: 400;
    transform: translateX(-105%);
    transition: transform var(--motion-duration-sidebar, 0.28s) var(--motion-ease-standard, cubic-bezier(0.4, 0, 0.2, 1));
    pointer-events: none;
    overflow: visible;
    will-change: transform;
  }

  .app.sidebar-mobile-open .sidebar-region {
    transform: translateX(0);
    pointer-events: auto;
  }

  .app.sidebar-collapsed .sidebar-region,
  .app:not(.sidebar-mobile-open) .sidebar-region {
    width: var(--sidebar-drawer-width);
  }

  .sidebar-shell {
    position: relative;
    z-index: 2;
    width: 100%;
    height: 100dvh;
    height: 100%;
    pointer-events: auto;
  }

  .sidebar {
    display: flex;
    width: 100%;
    height: 100%;
    transform: none;
    box-shadow: 8px 0 32px rgba(0, 0, 0, 0.35);
    padding-bottom: env(safe-area-inset-bottom, 0);
    pointer-events: auto;
    touch-action: manipulation;
  }

  .chat-history,
  .new-chat-btn,
  .account-btn,
  .history-item {
    touch-action: manipulation;
  }

  .sidebar-toggle {
    display: none;
  }

  .app-content {
    width: 100%;
    min-height: 0;
  }

  .mobile-menu-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    width: 40px;
    height: 40px;
    padding: 0;
    border: none;
    border-radius: 10px;
    background: var(--bg-input);
    color: var(--text-primary);
    cursor: pointer;
    -webkit-tap-highlight-color: transparent;
  }

  .mobile-menu-btn:hover,
  .mobile-menu-btn[aria-expanded="true"] {
    background: var(--bg-hover);
  }

  .model-select-wrap {
    top: max(8px, env(safe-area-inset-top, 0));
    left: max(8px, env(safe-area-inset-left, 0));
    right: max(8px, env(safe-area-inset-right, 0));
  }

  .model-select-column {
    flex: 1 1 auto;
    min-width: 0;
    max-width: calc(100% - 132px);
    padding-right: 8px;
  }

  .chat-header-actions {
    top: max(0px, env(safe-area-inset-top, 0));
    right: max(0px, env(safe-area-inset-right, 0));
    gap: 6px;
  }

  .model-select-left {
    width: 100%;
  }

  .private-chat-toggle {
    flex: 0 0 auto;
    padding: 4px 6px;
  }

  .private-chat-toggle-label {
    max-width: 120px;
  }

  .private-chat-hint {
    display: none;
  }

  .private-chat-toggle-text {
    font-size: 0.72rem;
  }

  .chat-share-btn {
    padding: 6px 8px;
  }

  .chat-share-btn-label {
    display: none;
  }

  .model-select-btn {
    min-width: 0;
    flex: 1;
    align-items: center;
    justify-content: space-between;
    padding: 8px 10px;
    background: var(--bg-input);
    border: 1px solid var(--border);
  }

  .model-select-trigger-wrap {
    flex: 1;
    min-width: 0;
  }

  .model-select-trigger,
  .model-select-trigger-desc {
    max-width: 100%;
  }

  .model-select-trigger {
    font-size: 0.82rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
  }

  .model-select-trigger-desc {
    font-size: 0.65rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  .model-select-menu {
    left: 0;
    right: 0;
    min-width: 0;
    max-width: 100%;
  }

  #view-chat.is-active .chat-area,
  #view-projects.is-active .chat-area {
    padding-top: 56px;
  }

  #chatMain.private-chat-active .chat-conversation {
    margin: 0 8px 6px;
    border-radius: 12px;
  }

  #chatMain.private-chat-active .chat-area {
    padding-bottom: 1.75rem;
  }

  .private-chat-frame-notice {
    left: 20px;
    bottom: calc(12px + 20px + 3rem + env(safe-area-inset-bottom, 0px));
    max-width: min(280px, calc(100% - 40px));
    font-size: 0.62rem;
  }

  .welcome {
    padding: 16px 12px 24px;
  }

  .welcome h1 {
    font-size: 1.35rem;
    text-align: center;
  }

  .suggestions {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .suggestion {
    padding: 12px 14px;
    font-size: 0.82rem;
  }

  .messages {
    padding: 12px 12px 88px;
    gap: 6px;
  }

  .message {
    max-width: 92%;
    gap: 8px;
  }

  .message-avatar {
    width: 28px;
    height: 28px;
    font-size: 0.65rem;
  }

  .message-content {
    font-size: 0.9rem;
  }

  .message.user .message-content {
    padding: 10px 14px;
  }

  .message-edit-actions {
    flex-wrap: wrap;
  }

  .input-area {
    padding: 10px 10px max(14px, env(safe-area-inset-bottom, 0));
  }

  .input-wrapper {
    max-width: none;
  }

  .input-row {
    min-height: 48px;
    padding: 4px 8px 4px 6px;
  }

  .project-mode-select-btn {
    max-width: 118px;
    height: 40px;
    font-size: 0.76rem;
  }

  .project-mode-select-menu {
    min-width: 132px;
  }

  .input-tool-btn,
  .send-btn {
    width: 40px;
    height: 40px;
  }

  .chat-message-input,
  #messageInput {
    font-size: 16px;
  }

  .attach-menu {
    left: 0;
    right: auto;
    max-width: calc(100vw - 24px);
  }

  #chatMain.chat-main--welcome .input-area,
  #projectsMain.projects-main--welcome .input-area {
    margin-top: 16px;
  }

  .settings-header {
    padding: max(12px, env(safe-area-inset-top, 0)) 16px 12px 16px;
  }

  .settings-header-inner {
    flex-wrap: wrap;
    gap: 12px;
  }

  .settings-back {
    font-size: 0.85rem;
  }

  .settings-header-title {
    font-size: 1.15rem;
  }

  .settings-body {
    flex-direction: column;
    min-height: 0;
  }

  .settings-nav {
    width: 100%;
    flex-shrink: 0;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 10px 12px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .settings-nav-list {
    flex-direction: row;
    gap: 6px;
  }

  .settings-nav-item {
    flex-shrink: 0;
    white-space: nowrap;
    padding: 8px 12px;
    font-size: 0.85rem;
  }

  .settings-panels {
    padding: 16px 14px max(24px, env(safe-area-inset-bottom, 0));
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
  }

  .settings-panel {
    max-width: none;
  }

  .settings-card {
    padding: 18px 16px;
  }

  .settings-form-footer {
    flex-direction: column;
    align-items: stretch;
  }

  .settings-form-footer .settings-btn {
    width: 100%;
  }

  .settings-info-row {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
  }

  .billing-body {
    padding: 12px 14px max(28px, env(safe-area-inset-bottom, 0));
  }

  .billing-page-header {
    padding: 16px 14px 12px;
  }

  .billing-page-header .settings-header-inner {
    align-items: flex-start;
    max-width: none;
  }

  .tasks-page-header {
    padding: 16px 14px 12px;
  }

  .tasks-page-header .tasks-header-inner {
    align-items: flex-start;
  }

  .tasks-header-actions {
    width: 100%;
    justify-content: flex-end;
  }

  .tasks-card {
    width: min(260px, calc(100vw - 56px));
  }

  .billing-content {
    gap: 28px;
  }

  .billing-content .settings-card {
    padding: 20px 18px;
  }

  .billing-section[aria-labelledby="billing-prepaid-heading"] {
    display: flex;
    flex-direction: column;
    gap: 12px;
  }

  .billing-section:first-child:has(.billing-plans-panel:not(.hidden)) {
    display: flex;
    flex-direction: column;
  }

  .billing-plan-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .billing-plan-actions .settings-btn {
    width: 100%;
  }

  .billing-topup-presets {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .billing-usage-grid {
    grid-template-columns: 1fr;
  }

  .billing-plans-grid {
    grid-template-columns: 1fr;
  }

  .billing-coupon-input-row {
    flex-direction: column;
    align-items: stretch;
  }

  .billing-coupon-submit {
    width: 100%;
  }

  .admin-table-wrap {
    margin: 0 -4px;
    -webkit-overflow-scrolling: touch;
  }

  .admin-table th,
  .admin-table td {
    padding: 8px 10px;
    font-size: 0.8rem;
  }

  .admin-detail-grid {
    grid-template-columns: 1fr;
  }

  .admin-plans-grid {
    grid-template-columns: 1fr;
  }

  .admin-payments-table {
    display: block;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .admin-detail-footer {
    flex-direction: column;
    align-items: stretch;
  }

  .admin-detail-footer .settings-btn,
  .admin-detail-footer .admin-row-btn {
    width: 100%;
  }

  .admin-user-create-form .admin-detail-grid {
    grid-template-columns: 1fr;
  }

  .api-key-modal {
    padding: 12px;
    align-items: flex-end;
  }

  .api-key-dialog {
    max-width: none;
    max-height: 90dvh;
    overflow-y: auto;
    border-radius: 16px 16px 0 0;
    padding-bottom: max(20px, env(safe-area-inset-bottom, 0));
  }

  .auth-page {
    padding: max(12px, env(safe-area-inset-top, 0)) 12px max(12px, env(safe-area-inset-bottom, 0));
    align-items: flex-start;
  }

  .auth-layout {
    border-radius: 0;
    box-shadow: none;
  }

  .auth-panel {
    padding: 28px 20px 32px;
  }

  .auth-field input {
    font-size: 16px;
  }
}

@media (max-width: 480px) {
  .billing-prepaid-balance-amount {
    font-size: 1.85rem;
  }

  .history-item-title {
    font-size: 0.82rem;
  }

  .new-chat-btn {
    padding: 10px 12px;
    font-size: 0.85rem;
  }
}

@media (max-width: 768px) and (prefers-reduced-motion: reduce) {
  .sidebar-region,
  .sidebar-backdrop {
    transition-duration: 0.01ms;
  }

  .sidebar-region {
    will-change: auto;
  }
}

@media (max-width: 768px) and (orientation: landscape) {
  .welcome h1 {
    font-size: 1.15rem;
  }

  #chatMain.chat-main--welcome .input-area,
  #projectsMain.projects-main--welcome .input-area {
    margin-top: 12px;
  }
}

@media (max-width: 640px) {
  .chat-image-lightbox-details {
    top: auto;
    bottom: max(16px, env(safe-area-inset-bottom));
    left: max(12px, env(safe-area-inset-left));
    right: max(12px, env(safe-area-inset-right));
    width: auto;
    max-height: 45vh;
  }

  .chat-image-lightbox-stage {
    padding-bottom: 72px;
  }

  .chat-image-lightbox-tool {
    width: 40px;
    height: 40px;
  }
}