diff --git a/renderers/angular/src/v0_9/catalog/basic/column.component.ts b/renderers/angular/src/v0_9/catalog/basic/column.component.ts
index 03a64db5d..30c37b514 100644
--- a/renderers/angular/src/v0_9/catalog/basic/column.component.ts
+++ b/renderers/angular/src/v0_9/catalog/basic/column.component.ts
@@ -15,11 +15,10 @@
  */
 
 import { Component, computed, ChangeDetectionStrategy } from '@angular/core';
+import { mapJustify, mapAlign } from '@a2ui/web_core/v0_9/basic_catalog';
 import { ComponentHostComponent } from '../../core/component-host.component';
-
 import { getNormalizedPath } from '../../core/utils';
 import { BasicCatalogComponent } from './basic-catalog-component';
-import { JUSTIFY_MAP, ALIGN_MAP } from './utils';
 
 /**
  * Angular implementation of the A2UI Column component (v0.9).
@@ -63,14 +62,8 @@ import { JUSTIFY_MAP, ALIGN_MAP } from './utils';
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class ColumnComponent extends BasicCatalogComponent {
-  protected readonly justify = computed(() => {
-    const val = this.props()['justify']?.value();
-    return val ? JUSTIFY_MAP[val] || val : undefined;
-  });
-  protected readonly align = computed(() => {
-    const val = this.props()['align']?.value();
-    return val ? ALIGN_MAP[val] || val : undefined;
-  });
+  protected readonly justify = computed(() => mapJustify(this.props()['justify']?.value()));
+  protected readonly align = computed(() => mapAlign(this.props()['align']?.value()));
 
   protected readonly children = computed(() => {
     const raw = this.props()['children']?.value() || [];
diff --git a/renderers/angular/src/v0_9/catalog/basic/row.component.ts b/renderers/angular/src/v0_9/catalog/basic/row.component.ts
index 3044f2675..29edcd5f3 100644
--- a/renderers/angular/src/v0_9/catalog/basic/row.component.ts
+++ b/renderers/angular/src/v0_9/catalog/basic/row.component.ts
@@ -15,10 +15,10 @@
  */
 
 import { Component, computed, ChangeDetectionStrategy } from '@angular/core';
+import { mapJustify, mapAlign } from '@a2ui/web_core/v0_9/basic_catalog';
 import { ComponentHostComponent } from '../../core/component-host.component';
 import { getNormalizedPath } from '../../core/utils';
 import { BasicCatalogComponent } from './basic-catalog-component';
-import { JUSTIFY_MAP, ALIGN_MAP } from './utils';
 
 /**
  * Angular implementation of the A2UI Row component (v0.9).
@@ -61,14 +61,8 @@ import { JUSTIFY_MAP, ALIGN_MAP } from './utils';
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class RowComponent extends BasicCatalogComponent {
-  protected readonly justify = computed(() => {
-    const val = this.props()['justify']?.value();
-    return val ? JUSTIFY_MAP[val] || val : undefined;
-  });
-  protected readonly align = computed(() => {
-    const val = this.props()['align']?.value();
-    return val ? ALIGN_MAP[val] || val : undefined;
-  });
+  protected readonly justify = computed(() => mapJustify(this.props()['justify']?.value()));
+  protected readonly align = computed(() => mapAlign(this.props()['align']?.value()));
 
   protected readonly children = computed(() => {
     const raw = this.props()['children']?.value() || [];
diff --git a/renderers/angular/src/v0_9/catalog/basic/utils.ts b/renderers/angular/src/v0_9/catalog/basic/utils.ts
deleted file mode 100644
index a46513362..000000000
--- a/renderers/angular/src/v0_9/catalog/basic/utils.ts
+++ /dev/null
@@ -1,39 +0,0 @@
-/**
- * Copyright 2026 Google LLC
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/**
- * Maps A2UI justification values to CSS justify-content values.
- */
-export const JUSTIFY_MAP: Record<string, string> = {
-  start: 'flex-start',
-  center: 'center',
-  end: 'flex-end',
-  spaceBetween: 'space-between',
-  spaceAround: 'space-around',
-  spaceEvenly: 'space-evenly',
-  stretch: 'stretch',
-};
-
-/**
- * Maps A2UI alignment values to CSS align-items values.
- */
-export const ALIGN_MAP: Record<string, string> = {
-  start: 'flex-start',
-  center: 'center',
-  end: 'flex-end',
-  stretch: 'stretch',
-  baseline: 'baseline',
-};
diff --git a/renderers/react/src/v0_9/catalog/basic/utils.ts b/renderers/react/src/v0_9/catalog/basic/utils.ts
index e2421afde..68949b69d 100644
--- a/renderers/react/src/v0_9/catalog/basic/utils.ts
+++ b/renderers/react/src/v0_9/catalog/basic/utils.ts
@@ -29,41 +29,7 @@ export const useBasicCatalogStyles = () => {
   }, []);
 };
 
-export const mapJustify = (j?: string) => {
-  switch (j) {
-    case 'center':
-      return 'center';
-    case 'end':
-      return 'flex-end';
-    case 'spaceAround':
-      return 'space-around';
-    case 'spaceBetween':
-      return 'space-between';
-    case 'spaceEvenly':
-      return 'space-evenly';
-    case 'start':
-      return 'flex-start';
-    case 'stretch':
-      return 'stretch';
-    default:
-      return 'flex-start';
-  }
-};
-
-export const mapAlign = (a?: string) => {
-  switch (a) {
-    case 'start':
-      return 'flex-start';
-    case 'center':
-      return 'center';
-    case 'end':
-      return 'flex-end';
-    case 'stretch':
-      return 'stretch';
-    default:
-      return 'stretch';
-  }
-};
+export {mapJustify, mapAlign} from '@a2ui/web_core/v0_9/basic_catalog';
 
 export const getBaseLeafStyle = (): React.CSSProperties => ({
   boxSizing: 'border-box',
diff --git a/renderers/web_core/src/v0_9/basic_catalog/index.ts b/renderers/web_core/src/v0_9/basic_catalog/index.ts
index 570513e6d..d448b1706 100644
--- a/renderers/web_core/src/v0_9/basic_catalog/index.ts
+++ b/renderers/web_core/src/v0_9/basic_catalog/index.ts
@@ -18,4 +18,5 @@ export * from './expressions/expression_parser.js';
 export * from './functions/basic_functions.js';
 export * from './functions/basic_functions_api.js';
 export * from './components/basic_components.js';
+export * from './styles/layout.js';
 export {injectBasicCatalogStyles} from './styles/default.js';
diff --git a/renderers/web_core/src/v0_9/basic_catalog/styles/layout.test.ts b/renderers/web_core/src/v0_9/basic_catalog/styles/layout.test.ts
new file mode 100644
index 000000000..9b6179e01
--- /dev/null
+++ b/renderers/web_core/src/v0_9/basic_catalog/styles/layout.test.ts
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {describe, it} from 'node:test';
+import * as assert from 'node:assert';
+
+import {mapAlign, mapJustify} from './layout.js';
+
+describe('mapJustify', () => {
+  it('maps center to center', () => {
+    assert.strictEqual(mapJustify('center'), 'center');
+  });
+  it('maps end to flex-end', () => {
+    assert.strictEqual(mapJustify('end'), 'flex-end');
+  });
+  it('maps spaceAround to space-around', () => {
+    assert.strictEqual(mapJustify('spaceAround'), 'space-around');
+  });
+  it('maps spaceBetween to space-between', () => {
+    assert.strictEqual(mapJustify('spaceBetween'), 'space-between');
+  });
+  it('maps spaceEvenly to space-evenly', () => {
+    assert.strictEqual(mapJustify('spaceEvenly'), 'space-evenly');
+  });
+  it('maps start to flex-start', () => {
+    assert.strictEqual(mapJustify('start'), 'flex-start');
+  });
+  it('maps stretch to stretch', () => {
+    assert.strictEqual(mapJustify('stretch'), 'stretch');
+  });
+  it('returns undefined for undefined input so consumers leave the style unset', () => {
+    assert.strictEqual(mapJustify(undefined), undefined);
+  });
+  it('returns undefined for null input', () => {
+    assert.strictEqual(mapJustify(null), undefined);
+  });
+  it('passes through unknown values unchanged', () => {
+    assert.strictEqual(mapJustify('unknown'), 'unknown');
+  });
+  it('does not resolve Object.prototype keys such as toString', () => {
+    assert.strictEqual(mapJustify('toString'), 'toString');
+  });
+  it('passes through empty string unchanged', () => {
+    assert.strictEqual(mapJustify(''), '');
+  });
+});
+
+describe('mapAlign', () => {
+  it('maps center to center', () => {
+    assert.strictEqual(mapAlign('center'), 'center');
+  });
+  it('maps end to flex-end', () => {
+    assert.strictEqual(mapAlign('end'), 'flex-end');
+  });
+  it('maps start to flex-start', () => {
+    assert.strictEqual(mapAlign('start'), 'flex-start');
+  });
+  it('maps stretch to stretch', () => {
+    assert.strictEqual(mapAlign('stretch'), 'stretch');
+  });
+  it('maps baseline to baseline', () => {
+    assert.strictEqual(mapAlign('baseline'), 'baseline');
+  });
+  it('returns undefined for undefined input so consumers leave the style unset', () => {
+    assert.strictEqual(mapAlign(undefined), undefined);
+  });
+  it('returns undefined for null input', () => {
+    assert.strictEqual(mapAlign(null), undefined);
+  });
+  it('passes through unknown values unchanged', () => {
+    assert.strictEqual(mapAlign('unknown'), 'unknown');
+  });
+  it('does not resolve Object.prototype keys such as toString', () => {
+    assert.strictEqual(mapAlign('toString'), 'toString');
+  });
+  it('passes through empty string unchanged', () => {
+    assert.strictEqual(mapAlign(''), '');
+  });
+});
diff --git a/renderers/web_core/src/v0_9/basic_catalog/styles/layout.ts b/renderers/web_core/src/v0_9/basic_catalog/styles/layout.ts
new file mode 100644
index 000000000..17ff75269
--- /dev/null
+++ b/renderers/web_core/src/v0_9/basic_catalog/styles/layout.ts
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Centralized layout mapping utilities for Web/CSS-based renderers.
+ *
+ * Maps A2UI layout enum values (e.g., `spaceBetween`) to their corresponding
+ * CSS values (e.g., `space-between`). These functions are shared across all
+ * web renderers (React, Lit, Angular) to ensure consistent behavior.
+ *
+ * Contract: nullish input returns `undefined` so consumers leave the CSS
+ * property unset (inherits from cascade / CSS variables). Unknown keys are
+ * passed through as-is so that future enum additions or spec mismatches
+ * remain visible to the browser rather than silently coerced to a default.
+ *
+ * The maps use `Map` rather than plain objects to avoid prototype-chain
+ * lookups (e.g. `mapJustify('toString')` must not hit `Object.prototype`).
+ */
+
+const justifyMap = new Map<string, string>([
+  ['center', 'center'],
+  ['end', 'flex-end'],
+  ['spaceAround', 'space-around'],
+  ['spaceBetween', 'space-between'],
+  ['spaceEvenly', 'space-evenly'],
+  ['start', 'flex-start'],
+  ['stretch', 'stretch'],
+]);
+
+/**
+ * Maps an A2UI justify enum value to its CSS `justify-content` equivalent.
+ *
+ * @param value - An A2UI justify value such as `'start'`, `'center'`,
+ *   `'spaceBetween'`, etc.
+ * @returns The mapped CSS value, the raw input if the key is unknown, or
+ *   `undefined` if the input is nullish.
+ */
+export function mapJustify(value?: string | null): string | undefined {
+  if (value === undefined || value === null) return undefined;
+  return justifyMap.get(value) ?? value;
+}
+
+const alignMap = new Map<string, string>([
+  ['baseline', 'baseline'],
+  ['center', 'center'],
+  ['end', 'flex-end'],
+  ['start', 'flex-start'],
+  ['stretch', 'stretch'],
+]);
+
+/**
+ * Maps an A2UI align enum value to its CSS `align-items` equivalent.
+ *
+ * @param value - An A2UI align value such as `'start'`, `'center'`, `'end'`,
+ *   `'stretch'`, or `'baseline'`.
+ * @returns The mapped CSS value, the raw input if the key is unknown, or
+ *   `undefined` if the input is nullish.
+ */
+export function mapAlign(value?: string | null): string | undefined {
+  if (value === undefined || value === null) return undefined;
+  return alignMap.get(value) ?? value;
+}