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

@@ -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;

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");
       }
     }
   }