From eeda571729d78481f903a7e62f5b0da20ce602ee Mon Sep 17 00:00:00 2001
From: rnitta <attinyes@gmail.com>
Date: Fri, 18 Oct 2019 15:23:59 +0900
Subject: [PATCH] fix the behavior of sticky header

---
 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 2cfa4821af..a4e55cda67 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -591,6 +591,6 @@ function playpen_text(playpen) {
             menu.classList.remove('bordered');
         }
 
-        previousScrollTop = document.scrollingElement.scrollTop;
+        previousScrollTop = Math.max(document.scrollingElement.scrollTop, 0);
     }, { passive: true });
 })();