ISTWCMS-6230: Add base width to 2 column layouts so image gallery can do math

src/patterns/03-layouts/layout/layout--2-col/_layout--2-col.scss

@@ -2,24 +2,23 @@
 
 .layout--uw-2-col {
   display: grid;
+  grid-template-columns: 100%;
   gap: var(--grid-gap);
   &.larger-left {
     @media(min-width: $screen-md) {
-      grid-template-columns: minmax(0, 2fr) 1fr;
+      grid-template-columns: 66%  30%;
     }
   }
 
   &.larger-right {
     @media(min-width: $screen-md){
-      grid-template-columns: 1fr minmax(0, 2fr);
+      grid-template-columns: 30% 66%;
     }
   }
 
   &.even-split {
-    grid-template-columns: 100%;
-
     @media(min-width: $screen-md) {
-      grid-template-columns: repeat(2, 1fr);
+      grid-template-columns: repeat(2, minmax(0, 1fr));
     }
   }