From 9f21859846955dcebcf80764d619f1dd1f76f18b Mon Sep 17 00:00:00 2001
From: Katsuya HIDAKA <hidakatsuya@gmail.com>
Date: Fri, 9 Oct 2026 10:35:24 +0900
Subject: Fix Gantt navigation buttons shifting when the scrollbar appears or
 disappears

---
 app/assets/stylesheets/gantt.css | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/app/assets/stylesheets/gantt.css b/app/assets/stylesheets/gantt.css
index 345be731b..9434f9deb 100644
--- a/app/assets/stylesheets/gantt.css
+++ b/app/assets/stylesheets/gantt.css
@@ -22,7 +22,8 @@
   display: flex;
   align-items: flex-start;
   inline-size: 100%;
-  margin-block-end: 1em;
+  /* Reserve space for the horizontal scrollbar so navigation stays in place. */
+  min-block-size: calc(var(--gantt-pane-height) + 24px);
   overflow: hidden;
   /* Force LTR for Gantt even in RTL locales because column resizing, relation lines, and the progress line don't work in RTL yet. */
   direction: ltr;
@@ -393,6 +394,7 @@
 
   .gantt-chart {
     inline-size: max-content;
+    min-block-size: 0;
     overflow: visible;
   }
 
-- 
2.55.0