diff --git a/docs/DESIGN.md b/docs/DESIGN.md
index c0a81e19..ca03b93e 100644
--- a/docs/DESIGN.md
+++ b/docs/DESIGN.md
@@ -143,7 +143,8 @@ The chosen rendering of each rule is in the lab under "Decided". The primitives
   choice"), r8 and full width in a form, where it wears the field's frame (see-through, the ≥ 3:1 edge) and
   lines up with the inputs. Open is the accent edge and the chevron turned over.
 - **Checkbox, switch, slider (A6):** the browser's own controls tinted with `accent-color` (`Checkbox`,
-  `CheckRow`, `Slider`, `ColorInput`); the whole labelled row is the 44px target. Keyboard, screen reader and
+  `CheckRow`, `Slider`); `ColorInput` is the browser's colour well, which `accent-color` does not reach (it
+  tints only checkboxes, radios, ranges and progress bars). The whole labelled row is the 44px target. Keyboard, screen reader and
   forced-colours support come from the browser. The switch stays `form`'s `Switch`: no browser has a native
   one yet. A raw `<input>` or `<textarea>` outside those primitives is a lint error (a hidden file picker
   passes).
diff --git a/frontend/src/design-lab/batchC.tsx b/frontend/src/design-lab/batchC.tsx
index de643c7e..c3f624a9 100644
--- a/frontend/src/design-lab/batchC.tsx
+++ b/frontend/src/design-lab/batchC.tsx
@@ -23,8 +23,13 @@ import {
 import { Btn } from "./batchA";
 import { C1 } from "./batchCActions";
 import { Reference, Sample } from "./labKit";
-import { FADE_ABOVE_PANEL, FADE_BELOW_PANEL, H, LAYER, STRONG } from "./labTokens";
+import { FADE_ABOVE_PANEL, FADE_BELOW_PANEL, LAYER } from "./labTokens";
 import { SURFACE } from "../components/ui/surfaces";
+import { iconButtonClass } from "../components/ui/buttonStyles";
+import { fieldClass } from "../components/ui/fieldStyles";
+
+// The ui/ primitives' own classes on static spans: the lab draws what the app ships, not a copy.
+const ICON = iconButtonClass({ variant: "ghost", size: "sm" });
 
 // E28 S2 · Batch C — behaviour on touch and on a narrow window, DECIDED (owner, 2026-09-24): C1–C4 as
 // proposed; C5 is the owner's reworked Plex control set (found by the live player pass, E28 S2d: the
@@ -61,10 +66,10 @@ function FilterPanel() {
       <div className="flex items-center justify-between">
         <span className="font-semibold">Filters</span>
         <span className="flex gap-0.5">
-          <span className={clsx("grid place-items-center rounded-lg text-muted", H.iconSm, LAYER)}>
+          <span className={ICON}>
             <Pin className="h-3.5 w-3.5" />
           </span>
-          <span className={clsx("grid place-items-center rounded-lg text-muted", H.iconSm, LAYER)}>
+          <span className={ICON}>
             <X className="h-3.5 w-3.5" />
           </span>
         </span>
@@ -144,12 +149,11 @@ function Field({ label, value, focused }: { label: string; value: string; focuse
       <span className="font-medium">{label}</span>
       <span
         className={clsx(
-          // eslint-disable-next-line no-restricted-syntax -- a drawing of a field, not a label
-          "flex items-center rounded-lg border px-3 text-sm",
-          H.field,
-          focused && "ring-2 ring-accent",
+          fieldClass({ size: "md" }),
+          "flex items-center",
+          // The primitive's focus-within look, drawn: a mock span can hold no focus.
+          focused && "border-accent ring-1 ring-accent",
         )}
-        style={{ borderColor: STRONG }}
       >
         {value}
       </span>
@@ -173,7 +177,7 @@ function C4() {
           )}
         >
           Edit details
-          <span className={clsx("grid place-items-center rounded-lg text-muted", H.iconSm)}>
+          <span className={ICON}>
             <X className={ico} />
           </span>
         </div>
diff --git a/frontend/src/design-lab/batchCActions.tsx b/frontend/src/design-lab/batchCActions.tsx
index f2ba6c27..0caff28e 100644
--- a/frontend/src/design-lab/batchCActions.tsx
+++ b/frontend/src/design-lab/batchCActions.tsx
@@ -1,7 +1,8 @@
 import clsx from "clsx";
 import { Bookmark, Check, ListPlus, MoreHorizontal, Play } from "lucide-react";
 import { Reference, Sample } from "./labKit";
-import { H, LAYER } from "./labTokens";
+import { LAYER } from "./labTokens";
+import { iconButtonClass } from "../components/ui/buttonStyles";
 import { SURFACE } from "../components/ui/surfaces";
 
 // E28 S2 · Batch C, part 1 — action placement: the classification table (object × action → where it
@@ -312,10 +313,9 @@ function Table() {
 }
 
 function Card({ touch }: { touch: boolean }) {
-  const act = clsx(
-    "grid place-items-center rounded-lg bg-black/55 text-white",
-    touch ? "h-11 w-11" : H.iconSm,
-  );
+  // The IconButton `media` face (a dark button on a picture); the touch rendering shows the 44 box
+  // that a coarse pointer gives it (A3).
+  const act = clsx(iconButtonClass({ variant: "media", size: "sm" }), touch && "size-11");
   return (
     <div className={`${SURFACE.card} group flex w-60 flex-col gap-1.5 p-1.5`}>
       <div className="relative aspect-video overflow-hidden rounded-lg bg-linear-to-br from-accent/50 to-card">
diff --git a/frontend/src/design-lab/labTokens.ts b/frontend/src/design-lab/labTokens.ts
index 719258a1..a58c2f9e 100644
--- a/frontend/src/design-lab/labTokens.ts
+++ b/frontend/src/design-lab/labTokens.ts
@@ -1,17 +1,7 @@
 // The decided values the lab's reference renderings share (batches A and B, 2026-09-24). The colour
 // rules are real now (E28 S3a): each constant below names the index.css utility or token that holds
-// it, so the lab renders what the app ships. The height ladder moves into ui/Button in S3b.
-
-/** B1 compact ladder: explicit heights, so one toolbar row lines up at 28. */
-export const H = {
-  md: "h-8 px-3 text-sm gap-1.5",
-  sm: "h-7 px-2.5 text-sm gap-1.5",
-  xs: "h-6 px-2 text-xs gap-1",
-  iconSm: "w-7 h-7",
-  icon: "w-8 h-8",
-  field: "h-8",
-  bar: "h-7",
-} as const;
+// it, so the lab renders what the app ships. The height ladder lives in the primitives (ui/buttonStyles,
+// ui/fieldStyles), and a lab drawing takes their classes (F31).
 
 /** A4: the input edge, ≥ 3:1 against the page in every scheme and mode (index.css --edge-strong). */
 export const STRONG = "var(--edge-strong)";