diff --git a/web/sections/BandBlocks.tsx b/web/sections/BandBlocks.tsx
index 5f601d6..a44408d 100644
--- a/web/sections/BandBlocks.tsx
+++ b/web/sections/BandBlocks.tsx
@@ -18,8 +18,14 @@ import type { CanvasComponent, CanvasSection } from '../canvas';
  * ── Columns, because adding needs one ──
  *
  * A block goes IN a column, so a flat list cannot express adding one. A one-column band shows a single
- * button and never has to ask a question it has no answer to; a two-column band shows Add left and Add
- * right.
+ * button and never has to ask a question it has no answer to.
+ *
+ * A two-column band NAMES its columns. It used to leave them unlabelled and put the side on the
+ * buttons — "Add left", "Add right" — and that reads as a flat list of blocks with two odd buttons
+ * under it: a band whose only block was on the left looked like a band with nothing on the left and
+ * two ways to fix it. The side belongs on the GROUP, which is the thing that has one; the buttons then
+ * say what they do, and an empty column is visible as an empty column rather than inferred from the
+ * absence of something.
  *
  * ── Reorder is within a column ──
  *
@@ -80,7 +86,18 @@ export const BandBlocks = ({
   return (
     <div className="flex flex-col gap-1">
       {Array.from({ length: columns }, (_, column) => (
-        <div key={column} className="flex flex-col gap-0.5">
+        <div
+          key={column}
+          // Indented behind a rule when there are two, so where one column ends is something you see
+          // rather than something you count.
+          className={`flex flex-col gap-0.5 ${columns === 2 ? 'border-l border-border/60 pl-1.5' : ''}`}
+        >
+          {columns === 2 && (
+            <span className="px-1 pt-0.5 text-[10px] font-medium tracking-wide text-muted-foreground/60 uppercase">
+              {column === 0 ? 'Left' : 'Right'}
+            </span>
+          )}
+
           {blocksIn(column).map((block) => (
             <span
               key={block.id}
@@ -131,7 +148,7 @@ export const BandBlocks = ({
             onClick={() => onAdd(section, column)}
           >
             <Plus className="size-3" />
-            {columns === 2 ? (column === 0 ? 'Add left' : 'Add right') : 'Add block'}
+            Add block
           </Button>
         </div>
       ))}