ISTWCMS-5647: setting the max-width variable and using it in card

src/patterns/01-core/props/_layout.scss

@@ -3,4 +3,5 @@
   --layout-max-width: 75rem;
   --grid-gutter: var(--size-4);
   --grid-gap: var(--size-4);
+  --max-width: 47.0625rem;
 }

src/patterns/04-components/card/card--node/_card--node.scss

@@ -186,7 +186,7 @@
 
         // Width is experimental to match one of the max-widths in
         // layouts for narrower width page look.
-        @include uw-contained-width(47.0625rem);
+        @include uw-contained-width(var(--max-width));
       }
     }
     // CSS for displaying the title within the node :