diff --git a/app/components/primer/open_project/zen_mode_button.pcss b/app/components/primer/open_project/zen_mode_button.pcss
index 53725a9c8c..79bd2a718d 100644
--- a/app/components/primer/open_project/zen_mode_button.pcss
+++ b/app/components/primer/open_project/zen_mode_button.pcss
@@ -1,5 +1,5 @@
 /* CSS for ZenModeButton  */
 
 .zen-mode-button--active {
-box-shadow: 0 0 3px var(--borderColor-default) inset;
+box-shadow: 0 0 3px var(--borderColor-default) inset !important;
 }