Merge pull request #2768 from Automattic/fix/742

Illustratr: Solve fixed cover image bug

illustratr/blocks.css

@@ -36,13 +36,12 @@ Description: Used to style Gutenberg Blocks.
 /* Full Width */
 
 .alignfull {
-	width: calc(100vw - 52px); /* subtract 52px for body padding */
-	max-width: calc(100vw - 52px);
-	margin-left: 0;
-	margin-right: 0;
+	margin-left: calc(50% - 50vw + 26px);
+	margin-right: calc(50% - 50vw + 26px);
+	max-width: 100vw;
 	position: relative;
-	left: 50%;
-	transform: translateX( -50% );
+	width: calc(100vw - 52px); /* subtract 52px for body padding */
+
 }
 
 @media (min-width: 768px) {
@@ -569,4 +568,3 @@ hr.wp-block-separator {
 .has-black-background-color:active {
 	background-color: #24282d;
 }
-