Makes grid centered

Author: kkartunov

src/shared/components/Contentful/Viewport/index.jsx

@@ -83,7 +83,7 @@ function ViewportContentLoader(props) {
   }
 
   if (themeName === 'Grid') {
-    extraStylesForContainer = _.assign(extraStylesForContainer || {}, {
+    extraStylesForContainer = _.defaults(extraStylesForContainer || {}, {
       'grid-template-columns': `repeat(${grid.columns || 3}, 1fr)`,
       'grid-gap': `${grid.gap || 10}px`,
     });

src/shared/components/Contentful/Viewport/themes/grid.scss

@@ -4,6 +4,7 @@
   display: grid;
   margin: 1em auto;
   overflow: auto;
+  justify-content: center;
 
   @include xl {
     max-width: $screen-lg;