diff --git a/REFERENCE.md b/REFERENCE.md
index 105bb81..28ae7b4 100644
--- a/REFERENCE.md
+++ b/REFERENCE.md
@@ -41,7 +41,7 @@ styles win without `!important`.
 | `.nv-button--pill` | pill button | Fully rounded. |
 | `.nv-button--block` | full-width button | Fills its container. |
 | `.nv-button__icon` | button icon slot | Sizes an inline SVG to the label. |
-| `.nv-button-group` | segmented control, button group | Buttons sharing edges; only outer corners round. |
+| `.nv-button-group` | segmented control, button group | Buttons sharing edges; only outer corners round. A button with `aria-pressed="true"` is drawn pressed in, in the brand colour. |
 
 States come from the element: `disabled`, `aria-disabled`, `aria-busy="true"`
 (shows a spinner and keeps the width), `aria-pressed` for toggles.
diff --git a/dist/niveus.css b/dist/niveus.css
index 2a76b82..e18d6e0 100644
--- a/dist/niveus.css
+++ b/dist/niveus.css
@@ -2283,6 +2283,16 @@
     z-index: 1;
     translate: none;
   }
+
+  /* The chosen segment is a key held down: pressed into the surface, in the
+     brand colour, rather than a flat wash. This is what makes the appearance
+     toggle (and any segmented choice) show which option is in use. */
+  .nv-button-group > .nv-button[aria-pressed="true"] {
+    background-color: var(--nv-color-accent-subtle);
+    background-image: none;
+    color: var(--nv-color-accent-text);
+    box-shadow: var(--nv-elevation-inset-sm), var(--nv-ledge);
+  }
 }
 @layer niveus.components {
   /* ==========================================================================
diff --git a/niveus/components/button.css b/niveus/components/button.css
index 9c4bb4d..567b962 100644
--- a/niveus/components/button.css
+++ b/niveus/components/button.css
@@ -312,3 +312,13 @@
   z-index: 1;
   translate: none;
 }
+
+/* The chosen segment is a key held down: pressed into the surface, in the
+   brand colour, rather than a flat wash. This is what makes the appearance
+   toggle (and any segmented choice) show which option is in use. */
+.nv-button-group > .nv-button[aria-pressed="true"] {
+  background-color: var(--nv-color-accent-subtle);
+  background-image: none;
+  color: var(--nv-color-accent-text);
+  box-shadow: var(--nv-elevation-inset-sm), var(--nv-ledge);
+}