Fixed offset styling for grid layout (#22)

Author: pederan

assets/css/hogan-gallery-grid.css

@@ -6,7 +6,7 @@
 	align-items: center;
 	display: flex;
 	flex-flow: row wrap;
-	margin: 0 -5px;
+	margin: -5px;
 
 	.hogan-gallery-cell {
 		flex: 0 0 calc(33.3333333% - 10px);
@@ -20,7 +20,7 @@
 
 @media screen and ( min-width: 700px ) {
 	.hogan-gallery-grid {
-		margin: 0 -10px;
+		margin: -10px;
 
 		.hogan-gallery-cell {
 			flex: 0 0 calc(25% - 20px);
@@ -31,7 +31,7 @@
 
 @media screen and ( min-width: 1200px ) {
 	.hogan-gallery-grid {
-		margin: 0 -15px;
+		margin: -15px;
 
 		.hogan-gallery-cell {
 			flex: 0 0 calc(25% - 30px);