@media (max-width: 900px) {
    .app-shell {
        display: block;
    }

    .sidebar {
        position: fixed;
        inset: 0 auto 0 0;
        z-index: 40;
        width: min(var(--sidebar-width), 86vw);
        transform: translateX(-100%);
        transition: transform 180ms ease;
        box-shadow: var(--shadow);
    }

    body.sidebar-collapsed .sidebar {
        width: min(var(--sidebar-width), 86vw);
        padding: 20px 16px;
        transform: translateX(-100%);
        border-right: 1px solid rgba(255, 255, 255, 0.08);
    }

    body.sidebar-collapsed.sidebar-expanded .sidebar {
        transform: translateX(0);
    }

    body.sidebar-collapsed .app-shell,
    body.sidebar-collapsed.sidebar-expanded .app-shell {
        display: block;
    }

    body.menu-open .sidebar {
        transform: translateX(0);
    }

    body.sidebar-collapsed.sidebar-expanded .mobile-overlay {
        display: block;
    }

    .menu-toggle {
        display: block;
        flex: 0 0 auto;
    }

    .mobile-overlay {
        position: fixed;
        inset: 0;
        z-index: 30;
        background: rgba(15, 23, 42, 0.42);
    }

    body.menu-open .mobile-overlay {
        display: block;
    }

    .topbar {
        min-height: 68px;
        padding: 12px 16px;
    }

    .notification-menu {
        margin-left: auto;
    }

    .notification-panel {
        position: fixed;
        top: 62px;
        right: 12px;
        left: 12px;
        width: auto;
        max-height: calc(100vh - 84px);
    }

    .topbar h1 {
        font-size: 20px;
    }

    .content {
        padding: 16px;
    }

    .panel {
        padding: 16px;
    }

    .panel-header,
    .split-panel {
        display: grid;
        grid-template-columns: 1fr;
    }

    .form-grid,
    .advanced-filters,
    .permission-grid,
    .field-config-grid,
    .iso9001-control-grid,
    .iso9001-detail-list {
        grid-template-columns: 1fr;
    }

    .header-actions,
    .dashboard-grid,
    .dashboard-panels,
    .dashboard-charts {
        grid-template-columns: 1fr;
    }

    .dashboard-status-card {
        grid-column: auto;
    }

    .dashboard-summary {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .donut-chart-layout {
        grid-template-columns: 1fr;
    }

    .column-chart {
        grid-template-columns: repeat(var(--column-count), minmax(64px, 1fr));
        overflow-x: auto;
        overflow-y: hidden;
    }

    .header-actions {
        display: grid;
        width: 100%;
    }

    .reading-list-page .reading-metrics {
        grid-template-columns: 1fr;
    }

    .pagination-bar,
    .pagination-summary {
        align-items: stretch;
        flex-direction: column;
    }

    .primary-button,
    .secondary-button,
    .form-actions .primary-button {
        width: auto;
    }

    .data-table {
        min-width: 980px;
    }

    .data-table thead {
        display: table-header-group;
    }

    .data-table tr {
        padding: 0;
        border-bottom: 0;
    }

    .data-table td {
        display: table-cell;
        width: auto;
        padding: 10px 9px;
        border-bottom: 1px solid var(--line);
    }

    .data-table td.actions {
        white-space: nowrap;
    }

    .data-table td::before,
    .data-table td.actions::before {
        content: none;
        display: none;
    }

    .actions a,
    .actions button {
        min-height: 34px;
        border: 1px solid var(--line);
        border-radius: 8px;
    }

    .document-table-wrap {
        overflow-x: auto;
    }

    .document-table {
        min-width: 1280px;
    }

    .document-table thead {
        display: table-header-group;
    }

    .document-table,
    .document-table tbody {
        display: table;
        width: 100%;
    }

    .document-table tbody {
        display: table-row-group;
    }

    .document-table tr {
        display: table-row;
        padding: 0;
        border-bottom: 0;
    }

    .document-table td {
        display: table-cell;
        width: auto;
        padding: 13px 12px;
        border-bottom: 1px solid var(--line);
    }

    .document-table td::before,
    .document-table td.actions::before {
        content: none;
        display: none;
    }

    .document-frame {
        min-height: 420px;
        height: 68vh;
    }

    .document-preview-modal {
        padding: 12px;
    }

    .document-preview-dialog {
        width: calc(100vw - 24px);
        max-height: calc(100vh - 24px);
    }

    .document-preview-header {
        align-items: stretch;
        flex-direction: column;
    }

    .document-preview-header .header-actions {
        display: grid;
        grid-template-columns: 1fr 1fr;
    }

    .document-preview-pages {
        grid-template-columns: 1fr;
        padding: 10px;
    }

    .code-builder-layout,
    .code-builder-options {
        grid-template-columns: 1fr;
    }

    .code-token-list {
        display: grid;
        overflow-x: visible;
    }

    .code-token {
        grid-template-columns: auto 1fr auto auto auto;
        min-width: 0;
    }

    .code-separator {
        width: 100%;
        flex-basis: auto;
    }

    .code-builder-main {
        padding: 12px;
        gap: 10px;
    }

    .code-builder-alert {
        max-width: none;
        padding: 10px 12px;
        font-size: 13px;
    }

    .code-builder-head {
        display: grid;
        grid-template-columns: minmax(0, 1fr) 62px;
        gap: 8px;
        font-size: 12px;
    }

    .code-order-list {
        grid-template-columns: minmax(0, 1fr) 62px;
        gap: 7px 8px;
    }

    .code-order-row {
        grid-column: 1;
        grid-template-columns: 28px minmax(0, 1fr) 58px;
        align-items: center;
        min-height: 38px;
        padding: 6px 8px;
    }

    .code-drag-handle {
        width: 24px;
        height: 28px;
    }

    .code-order-main {
        display: flex;
        gap: 6px;
    }

    .code-order-main span {
        font-size: 13px;
    }

    .code-order-main strong {
        padding: 2px 5px;
        font-size: 12px;
    }

    .code-order-actions {
        grid-column: auto;
        width: auto;
        justify-content: flex-end;
    }

    .code-order-actions button {
        flex: 0 0 auto;
        min-width: 25px;
        min-height: 26px;
    }

    .code-order-separator {
        grid-column: 2;
        margin: 0;
    }

    .code-order-separator span {
        display: none !important;
    }

    .code-order-separator input {
        width: 54px;
        min-height: 38px;
        padding: 5px 4px;
        font-size: 13px;
    }

    .code-builder-side {
        padding: 0;
    }

    .code-example-field {
        gap: 6px;
    }

    .code-example-field output {
        min-height: 38px;
        padding: 9px 11px;
        font-size: 14px;
    }

    .code-builder-options {
        gap: 10px;
        padding: 12px;
    }

    .responsible-row {
        grid-template-columns: 1fr minmax(96px, 130px);
        gap: 10px;
    }

    .associated-modal-panel {
        width: min(520px, 100vw);
        padding: 18px;
    }

    .document-action-drawer {
        width: 100vw;
        padding: 18px;
        border-left: 0;
    }

    .viewer-shell {
        margin: -16px;
    }

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

    .viewer-tools {
        display: grid;
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .viewer-body {
        grid-template-columns: 1fr;
    }

    .viewer-document {
        position: relative;
        padding: 10px;
    }

    .viewer-document iframe {
        width: 100%;
        height: 70vh;
        min-height: 460px;
    }

    .viewer-obsolete-watermark {
        top: 36vh;
        width: min(540px, 82%);
        font-size: clamp(30px, 11vw, 58px);
    }

    .viewer-details {
        position: fixed;
        inset: 0;
        z-index: 80;
        height: 100vh;
        border-left: 0;
    }

    body.viewer-details-closed .viewer-details {
        display: none;
    }

    .drawer-summary div {
        grid-template-columns: 1fr;
    }

    .row-actions {
        width: 100%;
    }

    .row-actions summary {
        width: 100%;
        text-align: center;
    }

    .row-actions > div {
        position: static;
        width: 100%;
    }

    .workflow-board,
    .task-meta {
        grid-template-columns: 1fr;
    }

    .task-card header,
    .revision-card header,
    .task-actions div {
        display: grid;
    }

    .task-actions .primary-button,
    .task-actions .secondary-button,
    .task-actions .danger-button {
        width: 100%;
    }

    .empty-state {
        min-height: calc(100vh - 100px);
        padding: 24px 18px;
    }
}