Add z-index to headline

Author: DanielCliftonGuardian

dotcom-rendering/src/components/ArticleHeadline.tsx

@@ -397,6 +397,8 @@ const galleryStyles = css`
 	${grid.between('grid-start', 'centre-column-end')}
 
 	grid-row: 7/9;
+	position: relative;
+	z-index: 2;
 
 	${from.tablet} {
 		${grid.between('centre-column-start', 'grid-end')};

dotcom-rendering/src/components/MainMediaGallery.tsx

@@ -22,6 +22,7 @@ const styles = css`
 	position: relative;
 	height: calc(80vh - 48px);
 	grid-row: 1/8;
+	z-index: 0;
 	${from.desktop} {
 		height: calc(100vh - 48px);
 	}