add column styling

templates/css/custom.css

@@ -116,4 +116,13 @@ caption {
     display: flow-root;
     margin: auto;
     width: 50%;
+}
+
+.column-wrapper {
+    display: flex;
+    flex-flow: row nowrap;
+}
+
+.column {
+    flex: 1 1 auto;
 }
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