diff --git a/resources/vivliostyle-viewport-screen.css b/resources/vivliostyle-viewport-screen.css
index ffe80c1c6..44079fbf9 100644
--- a/resources/vivliostyle-viewport-screen.css
+++ b/resources/vivliostyle-viewport-screen.css
@@ -33,17 +33,6 @@
         position: relative;
     }
 
-    [data-vivliostyle-layout-box] {
-        position: absolute;
-        left: 0;
-        top: 0;
-        z-index: -1;
-    }
-
-    [data-vivliostyle-debug] [data-vivliostyle-layout-box] {
-        z-index: auto;
-    }
-
     [data-vivliostyle-outer-zoom-box] {
         margin: auto;
         overflow: visible;
diff --git a/resources/vivliostyle-viewport.css b/resources/vivliostyle-viewport.css
index 8582f9429..183facd05 100644
--- a/resources/vivliostyle-viewport.css
+++ b/resources/vivliostyle-viewport.css
@@ -16,6 +16,17 @@
  *
  */
 
+[data-vivliostyle-layout-box] {
+    position: absolute;
+    left: 0;
+    top: 0;
+    z-index: -1;
+}
+
+[data-vivliostyle-debug] [data-vivliostyle-layout-box] {
+    z-index: auto;
+}
+
 [data-vivliostyle-page-container] {
     position: relative;
     overflow: hidden;