From 02507b9dafacda7b7e62beee11c496c72597c5e9 Mon Sep 17 00:00:00 2001
From: MurakamiShinyu <murakami@vivliostyle.org>
Date: Sat, 1 Mar 2025 00:29:08 +0900
Subject: [PATCH] fix: Do not remove table top border with thead and bottom
 border with tfoot at page break

When a table with `border-collapse: collapse` style is split across pages, the top border of the table should not be removed if the table has thead and the bottom border should not be removed if the table has tfoot.
---
 packages/core/src/vivliostyle/assets.ts | 4 ++--
 packages/core/src/vivliostyle/vgen.ts   | 7 ++-----
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/packages/core/src/vivliostyle/assets.ts b/packages/core/src/vivliostyle/assets.ts
index e3e2d8f7d..7a4ea8918 100644
--- a/packages/core/src/vivliostyle/assets.ts
+++ b/packages/core/src/vivliostyle/assets.ts
@@ -1423,14 +1423,14 @@ export const VivliostylePolyfillCss = `
   border-start-end-radius: 0 !important;
   border-end-end-radius: 0 !important;
 }
-[data-viv-box-break~="block-start"]:not([data-viv-box-break~="clone"]) {
+[data-viv-box-break~="block-start"]:not([data-viv-box-break~="clone"]):not(table[style*="border-collapse: collapse"]:has(>thead)) {
   margin-block-start: 0 !important;
   padding-block-start: 0 !important;
   border-block-start-width: 0 !important;
   border-start-start-radius: 0 !important;
   border-start-end-radius: 0 !important;
 }
-[data-viv-box-break~="block-end"]:not([data-viv-box-break~="clone"]) {
+[data-viv-box-break~="block-end"]:not([data-viv-box-break~="clone"]):not(table[style*="border-collapse: collapse"]:has(>tfoot)) {
   margin-block-end: 0 !important;
   padding-block-end: 0 !important;
   border-block-end-width: 0 !important;
diff --git a/packages/core/src/vivliostyle/vgen.ts b/packages/core/src/vivliostyle/vgen.ts
index b1dddf711..8d04c7efa 100644
--- a/packages/core/src/vivliostyle/vgen.ts
+++ b/packages/core/src/vivliostyle/vgen.ts
@@ -1536,11 +1536,8 @@ export class ViewFactory
             Break.setBoxBreakFlag(result, "block-start");
             if (Break.isCloneBoxDecorationBreak(result)) {
               Break.setBoxBreakFlag(result, "clone");
-
-              // When box-decoration-break: clone, cloned margins are always
-              // truncated to zero.
-              Break.setMarginDiscardFlag(result, "block-start");
             }
+            Break.setMarginDiscardFlag(result, "block-start");
           } else if (
             !Display.isAbsolutelyPositioned(computedStyle["position"])
           ) {
@@ -2632,8 +2629,8 @@ export class ViewFactory
         }
         if (Break.isCloneBoxDecorationBreak(elem)) {
           Break.setBoxBreakFlag(elem, "clone");
-          Break.setMarginDiscardFlag(elem, "block-end");
         }
+        Break.setMarginDiscardFlag(elem, "block-end");
       }
     }
   }