diff --git a/packages/ui/src/styles/design-system.css b/packages/ui/src/styles/design-system.css
index 69789087..f73b3603 100644
--- a/packages/ui/src/styles/design-system.css
+++ b/packages/ui/src/styles/design-system.css
@@ -58,7 +58,7 @@
     --sidebar-accent-foreground: oklch(0.25 0.02 40); /* Dark warm text */
     --sidebar-border: oklch(0.85 0.02 70); /* Warm border */
     --sidebar-ring: oklch(0.65 0.2 55); /* Focus ring */
-    --sidebar-stuck-bg: #DDDDD3; /* Desktop sidebar sticky header background */
+    --sidebar-stuck-bg: var(--sidebar); /* Desktop sidebar sticky header background (match sidebar) */
   }
 
   .dark {
@@ -95,7 +95,7 @@
     --sidebar-accent-foreground: oklch(0.85 0.02 90); /* #cdccc3 */
     --sidebar-border: oklch(0.31 0.01 35); /* #393836 */
     --sidebar-ring: oklch(0.77 0.17 85); /* #edb449 */
-    --sidebar-stuck-bg: #1F1F1D; /* Desktop sidebar sticky header background */
+    --sidebar-stuck-bg: var(--sidebar); /* Desktop sidebar sticky header background (match sidebar) */
   }
 
   * {