.mobile-only { display: none; }

@media (max-width: 1500px) {
  .messages { padding-inline: 20px; }
}

@media (max-width: 820px) {
  body { min-height: 100dvh; }
  .app-shell { grid-template-columns: 1fr; height: 100dvh; }
  .chat-pane { height: 100dvh; }
  .chat-pane::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 4;
    height: calc(58px + env(safe-area-inset-top));
    border-bottom: 1px solid var(--line);
    background: var(--bg);
    pointer-events: none;
  }
  .sidebar {
    position: fixed;
    inset: 0 auto 0 0;
    z-index: 10;
    width: min(86vw, 310px);
    height: 100dvh;
    padding-top: calc(18px + env(safe-area-inset-top));
    padding-bottom: calc(18px + env(safe-area-inset-bottom));
    transform: translateX(-105%);
    transition: transform .18s ease;
    box-shadow: none;
  }
  .sidebar.open { transform: translateX(0); }
  .mobile-only { display: grid; }
  #sidebarToggle {
    position: absolute;
    top: calc(9px + env(safe-area-inset-top));
    left: 12px;
    z-index: 5;
    padding-bottom: 2px;
    border: 1px solid var(--line);
    background: var(--panel);
    color: var(--text);
    font-size: 24px;
    line-height: 1;
    box-shadow: 0 1px 4px rgba(0,0,0,.08);
  }
  #sidebarToggle:hover, #sidebarToggle:focus-visible { background: var(--panel); color: var(--accent); }
  .messages { padding: calc(70px + env(safe-area-inset-top)) 14px 18px; }
  .composer {
    grid-template-columns: minmax(0, 1fr) 46px;
    gap: 8px;
    padding: 10px 12px calc(10px + env(safe-area-inset-bottom));
  }
  .composer.no-tree, .composer.no-keep, .composer.no-keep.no-tree { grid-template-columns: minmax(0, 1fr) 46px; }
  .composer textarea { grid-column: 1 / -1; grid-row: 2; order: 2; width: 100%; min-height: 46px; }
  .send-button, .composer.no-tree .send-button, .composer.no-keep .send-button, .composer.no-keep.no-tree .send-button {
    grid-column: 2;
    grid-row: 1;
    order: 1;
    width: 46px;
    height: 40px;
    border-radius: 14px;
  }
  .composer-actions { grid-column: 1; order: 1; display: flex; gap: 8px; align-items: center; }
  .composer-actions .model-toggle-button, .composer.no-tree .composer-actions .model-toggle-button, .composer.no-keep .composer-actions .model-toggle-button, .composer.no-keep.no-tree .composer-actions .model-toggle-button {
    grid-column: unset;
    margin-left: auto;
  }
  .composer-actions .keep-button, .composer-actions .icon-button, .special-actions .special-button {
    height: 40px;
    justify-content: center;
    padding: 0 8px;
    border: 1px solid var(--line);
    border-radius: 14px;
    background: var(--panel);
  }
  .composer-actions .icon-button { display: grid; width: 44px; }
  .composer-actions .model-toggle-button { height: 40px; }
  .special-menu { left: 0; right: auto; max-width: calc(100vw - 24px); }
  .pending-attachments { order: 3; width: 100%; }
  .jump-bottom { right: 18px; bottom: calc(124px + env(safe-area-inset-bottom)); }
  .tree-stage { padding: calc(78px + env(safe-area-inset-top)) 20px calc(40px + env(safe-area-inset-bottom)); }
  .search-page { padding: calc(78px + env(safe-area-inset-top)) 14px calc(24px + env(safe-area-inset-bottom)); }
  .search-result { grid-template-columns: minmax(0, 1fr); gap: 8px; }
  .search-result time { justify-self: start; }
}