diff --git a/src/contentscripts.js b/src/contentscripts.js
index d5b34046..a00a04f1 100644
--- a/src/contentscripts.js
+++ b/src/contentscripts.js
@@ -20,9 +20,9 @@ function focuseMode() {
     console.log( "=== simpread start ===" )
 
     var $focus, $parent,
-        sel, range, node,
-        tag, bakstyle,
-        mask = "z-index: auto; opacity: 1; overflow: visible; transform: none; animation: none; position: relative;";
+        sel, range, node, tag,
+        maskstyle  = "z-index: auto; opacity: 1; overflow: visible; transform: none; animation: none; position: relative;",
+        focusstyle = "z-index: 2147483647; overflow: visible; position: relative;";
 
     // find article tag
     if ( $( "body" ).find( "article" ).length > 0 ) {
@@ -43,14 +43,13 @@ function focuseMode() {
             return;
         }
     }
-    $focus.addClass( "ks-simpread-focus" );
+    focusStyle( $focus, focusstyle, "ks-simpread-focus", "add" );
 
     // add ks-simpread-mask
     $parent = $focus.parent();
     tag     = $parent[0].tagName;
     while ( tag.toLowerCase() != "body" ) {
-        bakstyle = $parent.attr( "style" ) == undefined ? "" : $parent.attr( "style" );
-        $parent.attr( "style", bakstyle + mask ).addClass("ks-simpread-mask");
+        focusStyle( $parent, maskstyle, "ks-simpread-mask", "add" );
         $parent = $parent.parent();
         tag     = $parent[0].tagName;
     }
@@ -60,20 +59,38 @@ function focuseMode() {
 
     // click mask remove it
     $( ".ks-simpread-bg" ).one( "click", function( event ) {
-        $focus.removeClass( "ks-simpread-focus" );
+        //$focus.removeClass( "ks-simpread-focus" );
+        focusStyle( $focus, focusstyle, "ks-simpread-focus", "delete" );
         $( ".ks-simpread-bg" ).remove();
 
         // remove ks-simpread-mask
         $parent = $focus.parent();
         tag     = $parent[0].tagName;
         while ( tag.toLowerCase() != "body" ) {
-            bakstyle = $parent.attr( "style" );
-            bakstyle = bakstyle.replace( mask, "" );
-            $parent.attr( "style", bakstyle ).removeClass( "ks-simpread-mask" );
+            focusStyle( $parent, maskstyle, "ks-simpread-mask", "delete" );
             $parent = $parent.parent();
             tag     = $parent[0].tagName;
         }
     });
 
     return false;
+}
+
+/*
+    Set focus style
+    @param $target: jquery object
+    @param style  : set style string
+    @param cls    : set class string
+    @param type   : include 'add' and 'delete'
+*/
+function focusStyle( $target, style, cls, type ) {
+    var bakstyle;
+    if ( type === "add" ) {
+        bakstyle = $target.attr( "style" ) == undefined ? "" : $target.attr( "style" );
+        $target.attr( "style", bakstyle + style ).addClass( cls );
+    } else if (  type === "delete" ) {
+        bakstyle = $target.attr( "style" );
+        bakstyle = bakstyle.replace( style, "" );
+        $target.attr( "style", bakstyle ).removeClass( cls );
+    }
 }
\ No newline at end of file