From a592da33bbf0adbe93d7d47fd016a8af462ed677 Mon Sep 17 00:00:00 2001
From: rnitta <attinyes@gmail.com>
Date: Sat, 19 Oct 2019 17:07:41 +0900
Subject: [PATCH] fix the behavior of sticky header (#1070)

---
 src/theme/book.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/theme/book.js b/src/theme/book.js
index dbeed295..1a419adb 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -602,6 +602,6 @@ function playpen_text(playpen) {
             menu.classList.remove('bordered');
         }
 
-        previousScrollTop = document.scrollingElement.scrollTop;
+        previousScrollTop = Math.max(document.scrollingElement.scrollTop, 0);
     }, { passive: true });
 })();