diff --git a/static/css/app.css b/static/css/app.css
index bb9f3de..c58523f 100644
--- a/static/css/app.css
+++ b/static/css/app.css
@@ -1698,7 +1698,7 @@ body.reader-immersive.reader-show-bottom .reader-overlay  { bottom: var(--bar-h)
   display: flex;
   align-items: center;
   justify-content: center;
-  background: var(--bg, #000);
+  background: rgba(20, 20, 20, 0.85);
   z-index: 10;
 }
 .pdf-loading-spinner {