New component: SubNav (Sidebar expansion)

.storybook/preview.tsx

@@ -9,7 +9,15 @@ import { ThemeSwapper, TextLight, TextDark } from "./ThemeSwapper";
 const TextThemeDiamondDS = "Theme: DiamondDS";
 
 export const decorators = [
-  (StoriesWithPadding: React.FC) => {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  (StoriesWithPadding: React.FC, context: any) => {
+    /* Fixed-position content (for example permanent Drawers) ignores this
+       wrapper's padding and stays aligned to the viewport, leaving a visible
+       gap beside padded content. 
+       Full-page layout stories opt out with this flag. */
+    if (context.parameters.fullBleed === true) {
+      return <StoriesWithPadding />;
+    }
     return (
       <div style={{ padding: "2em" }}>
         <StoriesWithPadding />

.storybook/storybook.css

@@ -1,3 +1,13 @@
+/* Gives the plain story canvas (not the Docs page, which sets its own
+   fixed height per docs.story.height) a definite height, so a story's
+   `minHeight: "100%"` resolves against the real viewport instead of
+   collapsing to its content's height. */
+html,
+body,
+#storybook-root {
+  height: 100%;
+}
+
 :root {
   --sb-ds-background: #f6f6f9;
   --sb-ds-surface: #ffffff;