diff --git a/libs/@guardian/design-tokens/src/tokens.json b/libs/@guardian/design-tokens/src/tokens.json
index 704d2bdb0..e636d7a3f 100644
--- a/libs/@guardian/design-tokens/src/tokens.json
+++ b/libs/@guardian/design-tokens/src/tokens.json
@@ -1537,7 +1537,7 @@
 					"fontSize": "{typography.fontSize.14}",
 					"lineHeight": "{typography.lineHeight.regular}",
 					"fontWeight": "{typography.fontWeight.regular}",
-					"fontStyle": "Italic"
+					"fontStyle": "italic"
 				}
 			},
 			"textSansItalic15": {
diff --git a/libs/@guardian/design-tokens/tokens.d.ts b/libs/@guardian/design-tokens/tokens.d.ts
index 6cc89de9d..2cf19f477 100644
--- a/libs/@guardian/design-tokens/tokens.d.ts
+++ b/libs/@guardian/design-tokens/tokens.d.ts
@@ -1444,7 +1444,7 @@ export declare const tokens: {
 				readonly fontSize: '14px';
 				readonly lineHeight: 1.3;
 				readonly fontWeight: 400;
-				readonly fontStyle: 'Italic';
+				readonly fontStyle: 'italic';
 			};
 			readonly textSansItalic15: {
 				readonly fontFamily: readonly [
diff --git a/libs/@guardian/design-tokens/tokens.js b/libs/@guardian/design-tokens/tokens.js
index 91ae76d49..24b562efe 100644
--- a/libs/@guardian/design-tokens/tokens.js
+++ b/libs/@guardian/design-tokens/tokens.js
@@ -1440,7 +1440,7 @@ export const tokens = {
 				fontSize: '14px',
 				lineHeight: 1.3,
 				fontWeight: 400,
-				fontStyle: 'Italic',
+				fontStyle: 'italic',
 			},
 			textSansItalic15: {
 				fontFamily: [
diff --git a/libs/@guardian/design-tokens/variables.css b/libs/@guardian/design-tokens/variables.css
index 57492a7c1..ac42bf5e7 100644
--- a/libs/@guardian/design-tokens/variables.css
+++ b/libs/@guardian/design-tokens/variables.css
@@ -1410,7 +1410,7 @@
 	--source-typography-presets-textSansItalic14-font-size: var(
 		--source-typography-fontSize-14
 	);
-	--source-typography-presets-textSansItalic14-font-style: Italic;
+	--source-typography-presets-textSansItalic14-font-style: italic;
 	--source-typography-presets-textSansItalic14-font-weight: var(
 		--source-typography-fontWeight-regular
 	);
diff --git a/libs/@guardian/source-foundations/src/tokens.test.ts b/libs/@guardian/source-foundations/src/tokens.test.ts
index 1949430ca..3136b215f 100644
--- a/libs/@guardian/source-foundations/src/tokens.test.ts
+++ b/libs/@guardian/source-foundations/src/tokens.test.ts
@@ -1870,7 +1870,7 @@ describe('Typography preset CSS output', () => {
 			font-size: 0.875rem;
 			line-height: 1.3;
 			font-weight: 400;
-			font-style: Italic;
+			font-style: italic;
 			--source-text-decoration-thickness: 2px;
 			`,
 			{ isFragment: true },
@@ -2681,7 +2681,7 @@ describe('Typography preset object output', () => {
 			fontSize: '0.875rem',
 			lineHeight: 1.3,
 			fontWeight: 400,
-			fontStyle: 'Italic',
+			fontStyle: 'italic',
 		});
 		expect(typePresetObject.textSansItalic15Object).toEqual({
 			fontFamily:
diff --git a/libs/@guardian/source-foundations/src/typography/css.ts b/libs/@guardian/source-foundations/src/typography/css.ts
index 1a9532a45..0eb43fcb6 100644
--- a/libs/@guardian/source-foundations/src/typography/css.ts
+++ b/libs/@guardian/source-foundations/src/typography/css.ts
@@ -790,7 +790,7 @@ export const textSansItalic14 = `
 	font-size: 0.875rem;
 	line-height: 1.3;
 	font-weight: 400;
-	font-style: Italic;
+	font-style: italic;
 	--source-text-decoration-thickness: 2px;
 `;
 
diff --git a/libs/@guardian/source-foundations/src/typography/objects.ts b/libs/@guardian/source-foundations/src/typography/objects.ts
index 8327bd06a..4fc4ce739 100644
--- a/libs/@guardian/source-foundations/src/typography/objects.ts
+++ b/libs/@guardian/source-foundations/src/typography/objects.ts
@@ -741,7 +741,7 @@ export const textSansItalic14Object = {
 	fontSize: '0.875rem',
 	lineHeight: 1.3,
 	fontWeight: 400,
-	fontStyle: 'Italic',
+	fontStyle: 'italic',
 } as const;
 
 export const textSansItalic15Object = {
diff --git a/libs/@guardian/source-foundations/src/typography/types.ts b/libs/@guardian/source-foundations/src/typography/types.ts
index 70865d6e8..0a830f934 100644
--- a/libs/@guardian/source-foundations/src/typography/types.ts
+++ b/libs/@guardian/source-foundations/src/typography/types.ts
@@ -115,3 +115,12 @@ export type Fs = <
 		unit: ScaleUnit;
 	},
 ) => TypographyStyles;
+
+export type TypographyPreset = `
+	font-family: ${string};
+	font-size: ${number}rem;
+	line-height: ${number};
+	font-weight: ${number};
+	font-style: ${'normal' | 'italic'};
+	--source-text-decoration-thickness: ${number}px;
+`;
diff --git a/libs/@guardian/source-foundations/src/utils/typography.test.ts b/libs/@guardian/source-foundations/src/utils/typography.test.ts
new file mode 100644
index 000000000..4e233e2aa
--- /dev/null
+++ b/libs/@guardian/source-foundations/src/utils/typography.test.ts
@@ -0,0 +1,30 @@
+import { headlineBold24, titlepiece42 } from '../typography/css';
+import { presetToPx } from './typography';
+
+describe('presetToPx', () => {
+	it('should convert preset font size value from rem to px', () => {
+		expect(presetToPx(headlineBold24)).toMatchCSS(
+			`
+			font-family: "GH Guardian Headline", "Guardian Egyptian Web", Georgia, serif;
+			font-size: 24px;
+			line-height: 1.15;
+			font-weight: 700;
+			font-style: normal;
+			--source-text-decoration-thickness: 3px;
+			`,
+			{ isFragment: true },
+		);
+
+		expect(presetToPx(titlepiece42)).toMatchCSS(
+			`
+			font-family: "GT Guardian Titlepiece", Georgia, serif;
+			font-size: 42px;
+			line-height: 1.15;
+			font-weight: 700;
+			font-style: normal;
+			--source-text-decoration-thickness: 5px;
+			`,
+			{ isFragment: true },
+		);
+	});
+});
diff --git a/libs/@guardian/source-foundations/src/utils/typography.ts b/libs/@guardian/source-foundations/src/utils/typography.ts
new file mode 100644
index 000000000..080bd49b8
--- /dev/null
+++ b/libs/@guardian/source-foundations/src/utils/typography.ts
@@ -0,0 +1,16 @@
+import type { TypographyPreset } from '../typography/types';
+
+/*
+ * Convert `font-size` value in typography preset from rem to px
+ */
+export const presetToPx = (preset: TypographyPreset) => {
+	const REGEX_FONT_SIZE = /font-size:\s(\d+\.\d+)rem/;
+
+	const matches = preset.match(REGEX_FONT_SIZE);
+	if (matches?.[1]) {
+		const pxVal = parseFloat(matches[1]) * 16;
+		return preset.replace(REGEX_FONT_SIZE, `font-size: ${pxVal}px`);
+	}
+
+	return preset;
+};