Fix product grids overflowing in some themes (#978)

Author: Aljullu

assets/css/style.scss

@@ -7,6 +7,7 @@
 }
 
 .wc-block-grid__product {
+	box-sizing: border-box;
 	padding: 0 $gap 0 0;
 	margin: 0 0 $gap-large 0;
 	float: none;