diff --git a/frontend/src/app/messages/[chatId]/page.tsx b/frontend/src/app/messages/[chatId]/page.tsx
index 0f94c106..7802ec32 100644
--- a/frontend/src/app/messages/[chatId]/page.tsx
+++ b/frontend/src/app/messages/[chatId]/page.tsx
@@ -1108,7 +1108,7 @@ function MessageDialogPageContent() {
                     <button
                       type="button"
                       onClick={() => void handleReturnToNewMessages()}
-                      className="app-action-primary relative inline-flex h-10 w-10 items-center justify-center rounded-full p-0 leading-none shadow-[var(--shadow-card)] active:scale-[0.98]"
+                      className="relative inline-flex h-10 w-10 items-center justify-center rounded-full border border-[var(--border-subtle)] bg-[var(--surface-primary)] p-0 leading-none text-[var(--muted-foreground)] shadow-[0_10px_30px_rgba(15,23,42,0.22)] transition hover:bg-[var(--surface-secondary)] hover:text-[var(--foreground)] active:scale-[0.98]"
                       title="Вернуться к новым сообщениям"
                       aria-label={displayedUnreadCount > 0 ? `Вернуться к новым сообщениям (${displayedUnreadCount > 99 ? "99+" : displayedUnreadCount})` : "Вернуться к новым сообщениям"}
                     >
diff --git a/frontend/src/components/AppShell.tsx b/frontend/src/components/AppShell.tsx
index 821b3b89..5f561387 100644
--- a/frontend/src/components/AppShell.tsx
+++ b/frontend/src/components/AppShell.tsx
@@ -339,10 +339,14 @@ function LeftNavContent({ onNavigate }: LeftNavContentProps) {
   );
 }
 
-function LeftNav() {
+function LeftNav({ fixedDesktop = false }: { fixedDesktop?: boolean }) {
   return (
-    <aside className="hidden w-64 flex-shrink-0 lg:block lg:sticky lg:self-start lg:top-8 lg:max-h-[calc(100vh-7.5rem)] lg:overflow-y-auto">
-      <div className="space-y-4 lg:pb-2">
+    <aside className="hidden w-64 flex-shrink-0 lg:block">
+      <div
+        className={`space-y-4 lg:max-h-[calc(100vh-7.5rem)] lg:overflow-y-auto lg:pb-2 ${
+          fixedDesktop ? "lg:fixed lg:top-[5.5rem] lg:w-64" : "lg:sticky lg:top-8"
+        }`}
+      >
         <LeftNavContent />
       </div>
     </aside>
@@ -455,7 +459,7 @@ export function AppShell({ children }: AppShellProps) {
           onOpenCalendar={() => setIsMobileCalendarOpen(true)}
         />
         <div className={`mx-auto flex w-full flex-1 min-h-0 max-w-6xl ${isMessageDialogPage ? 'gap-0 px-0 py-0 lg:gap-6 lg:px-8 lg:py-8' : 'gap-6 px-4 py-4 sm:px-8 lg:py-8'}`}>
-          <LeftNav />
+          <LeftNav fixedDesktop={!isMessageDialogPage} />
           <main className={`flex-1 min-w-0 min-h-0 space-y-6 ${isMessageDialogPage ? 'overflow-visible' : ''}`}>{children}</main>
           <CalendarSidebar
             onOpenCalendarModal={cal.handleOpenCalendarModal}