diff --git a/ROADMAP.md b/ROADMAP.md
index cb273f3c5..a3cbd7132 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -1,6 +1,6 @@
 # ObjectUI Development Roadmap
 
-> **Last Updated:** February 20, 2026
+> **Last Updated:** February 21, 2026
 > **Current Version:** v0.5.x
 > **Spec Version:** @objectstack/spec v3.0.8
 > **Client Version:** @objectstack/client v3.0.8
@@ -72,7 +72,8 @@ All 11 plugin views (Grid, Kanban, Form, Dashboard, Calendar, Timeline, List, De
 
 - Base `DialogContent` upgraded to mobile-first layout: full-screen on mobile (`inset-0 h-[100dvh]`), centered on desktop (`sm:inset-auto sm:max-w-lg sm:rounded-lg`), close button touch target ≥ 44×44px (WCAG 2.5.5).
 - `MobileDialogContent` custom component for ModalForm with flex layout (sticky header + scrollable body + sticky footer).
-- ModalForm: skeleton loading state, sticky action buttons, form grid forced to 1-column on mobile (`md:` breakpoint for multi-column).
+- ModalForm: skeleton loading state, sticky action buttons, container-query-based grid layout (`@container` + `@md:grid-cols-2`) ensures single-column on narrow mobile modals regardless of viewport width.
+- DrawerForm: container-query-based grid layout matching ModalForm, responsive to actual drawer width.
 - Date/DateTime fields use native HTML5 inputs (`type="date"`, `type="datetime-local"`) for optimal mobile picker UX.
 - Form sections supported via `ModalFormSectionConfig` for visual field grouping.
 
diff --git a/packages/plugin-form/src/DrawerForm.tsx b/packages/plugin-form/src/DrawerForm.tsx
index 6b8d32e7f..50bbcdfbe 100644
--- a/packages/plugin-form/src/DrawerForm.tsx
+++ b/packages/plugin-form/src/DrawerForm.tsx
@@ -28,6 +28,18 @@ import { SchemaRenderer } from '@object-ui/react';
 import { mapFieldTypeToFormType, buildValidationRules } from '@object-ui/fields';
 import { applyAutoLayout } from './autoLayout';
 
+/**
+ * Container-query-based grid classes for form field layout.
+ * Uses @container / @md: / @2xl: / @4xl: variants so that the grid
+ * responds to the drawer's actual width instead of the viewport.
+ */
+const CONTAINER_GRID_COLS: Record<number, string | undefined> = {
+  1: undefined,
+  2: 'grid gap-4 grid-cols-1 @md:grid-cols-2',
+  3: 'grid gap-4 grid-cols-1 @md:grid-cols-2 @2xl:grid-cols-3',
+  4: 'grid gap-4 grid-cols-1 @md:grid-cols-2 @2xl:grid-cols-3 @4xl:grid-cols-4',
+};
+
 export interface DrawerFormSectionConfig {
   name?: string;
   label?: string;
@@ -328,23 +340,27 @@ export const DrawerForm: React.FC<DrawerFormProps> = ({
     if (schema.sections?.length) {
       return (
         <div className="space-y-6">
-          {schema.sections.map((section, index) => (
-            <FormSection
-              key={section.name || section.label || index}
-              label={section.label}
-              description={section.description}
-              columns={section.columns || 1}
-            >
-              <SchemaRenderer
-                schema={{
-                  ...baseFormSchema,
-                  fields: buildSectionFields(section),
-                  showSubmit: index === schema.sections!.length - 1 && baseFormSchema.showSubmit,
-                  showCancel: index === schema.sections!.length - 1 && baseFormSchema.showCancel,
-                }}
-              />
-            </FormSection>
-          ))}
+          {schema.sections.map((section, index) => {
+            const sectionCols = section.columns || 1;
+            return (
+              <FormSection
+                key={section.name || section.label || index}
+                label={section.label}
+                description={section.description}
+                columns={sectionCols}
+                gridClassName={CONTAINER_GRID_COLS[sectionCols]}
+              >
+                <SchemaRenderer
+                  schema={{
+                    ...baseFormSchema,
+                    fields: buildSectionFields(section),
+                    showSubmit: index === schema.sections!.length - 1 && baseFormSchema.showSubmit,
+                    showCancel: index === schema.sections!.length - 1 && baseFormSchema.showCancel,
+                  }}
+                />
+              </FormSection>
+            );
+          })}
         </div>
       );
     }
@@ -352,13 +368,17 @@ export const DrawerForm: React.FC<DrawerFormProps> = ({
     // Apply auto-layout for flat fields (infer columns + colSpan)
     const autoLayoutResult = applyAutoLayout(formFields, objectSchema, schema.columns, schema.mode);
 
-    // Flat fields layout
+    // Flat fields layout — use container-query grid classes so the form
+    // responds to the drawer width, not the viewport width.
+    const containerFieldClass = CONTAINER_GRID_COLS[autoLayoutResult.columns || 1];
+
     return (
       <SchemaRenderer
         schema={{
           ...baseFormSchema,
           fields: autoLayoutResult.fields,
           columns: autoLayoutResult.columns,
+          ...(containerFieldClass ? { fieldContainerClass: containerFieldClass } : {}),
         }}
       />
     );
@@ -378,7 +398,7 @@ export const DrawerForm: React.FC<DrawerFormProps> = ({
           </SheetHeader>
         )}
 
-        <div className="py-4">
+        <div className="@container py-4">
           {renderContent()}
         </div>
       </SheetContent>
diff --git a/packages/plugin-form/src/FormSection.tsx b/packages/plugin-form/src/FormSection.tsx
index 778423b9b..2fd56a5e6 100644
--- a/packages/plugin-form/src/FormSection.tsx
+++ b/packages/plugin-form/src/FormSection.tsx
@@ -55,6 +55,13 @@ export interface FormSectionProps {
    * Additional CSS classes
    */
   className?: string;
+
+  /**
+   * Override the default responsive grid classes.
+   * When provided, replaces the viewport-based grid-cols classes
+   * (e.g. with container-query-based classes like `@md:grid-cols-2`).
+   */
+  gridClassName?: string;
 }
 
 /**
@@ -78,6 +85,7 @@ export const FormSection: React.FC<FormSectionProps> = ({
   columns = 1,
   children,
   className,
+  gridClassName,
 }) => {
   const [isCollapsed, setIsCollapsed] = useState(initialCollapsed);
 
@@ -133,7 +141,7 @@ export const FormSection: React.FC<FormSectionProps> = ({
 
       {/* Section Content */}
       {!isCollapsed && (
-        <div className={cn('grid gap-4', gridCols[columns])}>
+        <div className={cn('grid gap-4', gridClassName || gridCols[columns])}>
           {children}
         </div>
       )}
diff --git a/packages/plugin-form/src/ModalForm.tsx b/packages/plugin-form/src/ModalForm.tsx
index 8e633c0ab..5254653df 100644
--- a/packages/plugin-form/src/ModalForm.tsx
+++ b/packages/plugin-form/src/ModalForm.tsx
@@ -105,6 +105,19 @@ const modalSizeClasses: Record<string, string> = {
   full: 'max-w-[95vw] w-full',
 };
 
+/**
+ * Container-query-based grid classes for form field layout.
+ * Uses @container / @md: / @2xl: / @4xl: variants so that the grid
+ * responds to the modal's actual width instead of the viewport,
+ * ensuring single-column on narrow mobile modals regardless of viewport size.
+ */
+const CONTAINER_GRID_COLS: Record<number, string | undefined> = {
+  1: undefined, // let the form renderer use its default (space-y-4)
+  2: 'grid gap-4 grid-cols-1 @md:grid-cols-2',
+  3: 'grid gap-4 grid-cols-1 @md:grid-cols-2 @2xl:grid-cols-3',
+  4: 'grid gap-4 grid-cols-1 @md:grid-cols-2 @2xl:grid-cols-3 @4xl:grid-cols-4',
+};
+
 export const ModalForm: React.FC<ModalFormProps> = ({
   schema,
   dataSource,
@@ -364,22 +377,26 @@ export const ModalForm: React.FC<ModalFormProps> = ({
     if (schema.sections?.length) {
       return (
         <div className="space-y-6">
-          {schema.sections.map((section, index) => (
-            <FormSection
-              key={section.name || section.label || index}
-              label={section.label}
-              description={section.description}
-              columns={section.columns || 1}
-            >
-              <SchemaRenderer
-                schema={{
-                  ...baseFormSchema,
-                  fields: buildSectionFields(section),
-                  // Actions are in the sticky footer, not inside sections
-                }}
-              />
-            </FormSection>
-          ))}
+          {schema.sections.map((section, index) => {
+            const sectionCols = section.columns || 1;
+            return (
+              <FormSection
+                key={section.name || section.label || index}
+                label={section.label}
+                description={section.description}
+                columns={sectionCols}
+                gridClassName={CONTAINER_GRID_COLS[sectionCols]}
+              >
+                <SchemaRenderer
+                  schema={{
+                    ...baseFormSchema,
+                    fields: buildSectionFields(section),
+                    // Actions are in the sticky footer, not inside sections
+                  }}
+                />
+              </FormSection>
+            );
+          })}
         </div>
       );
     }
@@ -387,13 +404,17 @@ export const ModalForm: React.FC<ModalFormProps> = ({
     // Reuse pre-computed auto-layout result for flat fields
     const layoutResult = autoLayoutResult ?? applyAutoLayout(formFields, objectSchema, schema.columns, schema.mode);
 
-    // Flat fields layout
+    // Flat fields layout — use container-query grid classes so the form
+    // responds to the modal width, not the viewport width.
+    const containerFieldClass = CONTAINER_GRID_COLS[layoutResult.columns || 1];
+
     return (
       <SchemaRenderer
         schema={{
           ...baseFormSchema,
           fields: layoutResult.fields,
           columns: layoutResult.columns,
+          ...(containerFieldClass ? { fieldContainerClass: containerFieldClass } : {}),
         }}
       />
     );
@@ -411,7 +432,7 @@ export const ModalForm: React.FC<ModalFormProps> = ({
           </DialogHeader>
         )}
 
-        <div className="flex-1 overflow-y-auto px-4 sm:px-6 py-4">
+        <div className="@container flex-1 overflow-y-auto px-4 sm:px-6 py-4">
           {renderContent()}
         </div>
 
diff --git a/packages/plugin-form/src/__tests__/MobileUX.test.tsx b/packages/plugin-form/src/__tests__/MobileUX.test.tsx
index 7dea9e0aa..607643bb7 100644
--- a/packages/plugin-form/src/__tests__/MobileUX.test.tsx
+++ b/packages/plugin-form/src/__tests__/MobileUX.test.tsx
@@ -191,3 +191,133 @@ describe('ModalForm Mobile UX', () => {
     expect(screen.queryByTestId('modal-form-footer')).not.toBeInTheDocument();
   });
 });
+
+describe('ModalForm Container Query Layout', () => {
+  /** CSS selector for the @container query context element */
+  const CONTAINER_SELECTOR = '.\\@container';
+
+  it('applies @container class on scrollable content area', async () => {
+    const mockDataSource = createMockDataSource();
+
+    render(
+      <ModalForm
+        schema={{
+          type: 'object-form',
+          formType: 'modal',
+          objectName: 'events',
+          mode: 'create',
+          title: 'Create Event',
+          open: true,
+        }}
+        dataSource={mockDataSource as any}
+      />
+    );
+
+    await waitFor(() => {
+      expect(screen.getByText('Create Event')).toBeInTheDocument();
+    });
+
+    // The scrollable content wrapper should be a @container query context
+    const dialogContent = document.querySelector('[role="dialog"]');
+    expect(dialogContent).not.toBeNull();
+    const scrollArea = dialogContent!.querySelector(CONTAINER_SELECTOR);
+    expect(scrollArea).not.toBeNull();
+    expect(scrollArea!.className).toContain('overflow-y-auto');
+  });
+
+  it('uses container-query grid classes for multi-column flat fields', async () => {
+    // Mock schema with enough fields to trigger auto-layout 2-column
+    const manyFieldsSchema = {
+      name: 'contacts',
+      fields: {
+        name: { label: 'Name', type: 'text', required: true },
+        email: { label: 'Email', type: 'email', required: false },
+        phone: { label: 'Phone', type: 'phone', required: false },
+        company: { label: 'Company', type: 'text', required: false },
+        department: { label: 'Department', type: 'text', required: false },
+        title: { label: 'Title', type: 'text', required: false },
+      },
+    };
+    const mockDataSource = createMockDataSource();
+    mockDataSource.getObjectSchema.mockResolvedValue(manyFieldsSchema);
+
+    render(
+      <ModalForm
+        schema={{
+          type: 'object-form',
+          formType: 'modal',
+          objectName: 'contacts',
+          mode: 'create',
+          title: 'Create Contact',
+          open: true,
+        }}
+        dataSource={mockDataSource as any}
+      />
+    );
+
+    await waitFor(() => {
+      expect(screen.getByText('Create Contact')).toBeInTheDocument();
+    });
+
+    // Wait for fields to render
+    await waitFor(() => {
+      expect(screen.getByText('Name')).toBeInTheDocument();
+    });
+
+    // The form field container should use container-query classes (@md:grid-cols-2)
+    // instead of viewport-based classes (md:grid-cols-2)
+    const dialogContent = document.querySelector('[role="dialog"]');
+    const containerEl = dialogContent!.querySelector(CONTAINER_SELECTOR);
+    expect(containerEl).not.toBeNull();
+
+    // Look for the grid container with @md:grid-cols-2
+    const gridEl = containerEl!.querySelector('[class*="@md:grid-cols-2"]');
+    expect(gridEl).not.toBeNull();
+    expect(gridEl!.className).toContain('@md:grid-cols-2');
+    // Should NOT use viewport-based md:grid-cols-2 (without @ prefix)
+    expect(gridEl!.className).not.toContain(' md:grid-cols-2');
+  });
+
+  it('single-column forms do not get container grid override', async () => {
+    // Only 3 fields → auto-layout stays at 1 column
+    const fewFieldsSchema = {
+      name: 'notes',
+      fields: {
+        title: { label: 'Title', type: 'text', required: true },
+        body: { label: 'Body', type: 'textarea', required: false },
+        status: { label: 'Status', type: 'select', required: false, options: [{ value: 'draft', label: 'Draft' }] },
+      },
+    };
+    const mockDataSource = createMockDataSource();
+    mockDataSource.getObjectSchema.mockResolvedValue(fewFieldsSchema);
+
+    render(
+      <ModalForm
+        schema={{
+          type: 'object-form',
+          formType: 'modal',
+          objectName: 'notes',
+          mode: 'create',
+          title: 'Create Note',
+          open: true,
+        }}
+        dataSource={mockDataSource as any}
+      />
+    );
+
+    await waitFor(() => {
+      expect(screen.getByText('Create Note')).toBeInTheDocument();
+    });
+
+    await waitFor(() => {
+      expect(screen.getByText('Title')).toBeInTheDocument();
+    });
+
+    // Single column form should not have @md:grid-cols-2
+    const dialogContent = document.querySelector('[role="dialog"]');
+    const containerEl = dialogContent!.querySelector(CONTAINER_SELECTOR);
+    expect(containerEl).not.toBeNull();
+    const gridEl = containerEl!.querySelector('[class*="@md:grid-cols"]');
+    expect(gridEl).toBeNull();
+  });
+});