diff --git a/src/plugins/bookPlayer/style.scss b/src/plugins/bookPlayer/style.scss
index 694bb8b1e2..df96a9e5c5 100644
--- a/src/plugins/bookPlayer/style.scss
+++ b/src/plugins/bookPlayer/style.scss
@@ -15,7 +15,7 @@
         top: 0;
         width: 100%;
         color: #000;
-        opacity: .7;
+        opacity: 0.7;
     }
 
     .bookPlayerContainer {