edit

front/static/document.js

@@ -176,7 +176,7 @@ var Document =
         var w = c.width();
         var b = w/self.width;
         if (self.left) {
-            var z = 100-100/b + self.zoom;
+            var z = 100-(100/b) + self.zoom;
             $(self.option.reader).css('zoom', z + '%');
             c = c.children().eq(0);
             e = c.children().eq(0);