From a0c10adbaeff7ea2a56627521e3a49ce4186a967 Mon Sep 17 00:00:00 2001
From: neverland <chenjiahan@youzan.com>
Date: Sat, 22 Aug 2020 16:11:08 +0800
Subject: [PATCH] fix(Calendar): render error when using rem unit (#7037)

---
 src/calendar/index.js | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/calendar/index.js b/src/calendar/index.js
index 7f88475c5..857f08754 100644
--- a/src/calendar/index.js
+++ b/src/calendar/index.js
@@ -258,8 +258,15 @@ export default createComponent({
       let height = 0;
       let currentMonth;
 
+      // add offset to avoid rem accuracy issues
+      // see: https://github.com/youzan/vant/issues/6929
+      const viewportOffset = 50;
+      const viewportTop = top - viewportOffset;
+      const viewportBottom = bottom + viewportOffset;
+
       for (let i = 0; i < months.length; i++) {
-        const visible = height <= bottom && height + heights[i] >= top;
+        const visible =
+          height <= viewportBottom && height + heights[i] >= viewportTop;
 
         if (visible && !currentMonth) {
           currentMonth = months[i];