diff --git a/phpBB/styles/prosilver/theme/responsive.css b/phpBB/styles/prosilver/theme/responsive.css
index 774dc77b96..61c204026b 100644
--- a/phpBB/styles/prosilver/theme/responsive.css
+++ b/phpBB/styles/prosilver/theme/responsive.css
@@ -554,8 +554,9 @@
 
 @media (min-width: 701px) {
 	.postbody {
-		/** deduct postprofile width (including border width, margin and padding) */
-		width: calc(100% - 200px - 1px);
+		/** deduct postprofile width (including border width, margin and padding) and postbody margin and padding */
+		width: calc(100% - 200px - 1px - 16px);
+		margin-right: 16px;
 	}
 
 	.postprofile {