diff --git a/src/css/controller.scss b/src/css/controller.scss
index 7f3b030b0..9b2a88fd9 100644
--- a/src/css/controller.scss
+++ b/src/css/controller.scss
@@ -41,7 +41,7 @@
             background: #fff;
             pointer-events: none;
             display: none;
-            background-size: auto 100%;
+            background-size: 16000px 100%;
         }
         .dplayer-bar-preview-canvas {
             position: absolute;