make nav sticky

apps/app/src/pages/share/[[...path]].page.tsx

@@ -120,9 +120,9 @@ const SharedPage: NextPageWithLayout<Props> = (props: Props) => {
       </Head>
 
       <div className={`dynamic-layout-root ${growiLayoutFluidClass} justify-content-between`}>
-        <header className="py-0 position-relative">
+        <nav className="sticky-top">
           <GrowiContextualSubNavigationForSharedPage page={currentPage ?? props.shareLinkRelatedPage} isLinkSharingDisabled={props.disableLinkSharing} />
-        </header>
+        </nav>
 
         <div id="grw-fav-sticky-trigger" className="sticky-top"></div>