diff --git a/browser/themes/shared/tabbrowser/content-area.css b/browser/themes/shared/tabbrowser/content-area.css
index 5c721ee07f0be1318a50cb381ddf59550a04d496..fa2d21687dd8ea7dd03fb4cc2952fe783782a955 100644
--- a/browser/themes/shared/tabbrowser/content-area.css
+++ b/browser/themes/shared/tabbrowser/content-area.css
@@ -237,7 +237,7 @@
 
 .dialogStack {
   z-index: var(--browser-stack-z-index-dialog-stack);
-  position: absolute;
+  position: fixed;
   inset: 0;
 
   /* Hide tab-modal dialogs when a window-modal one is up. */
