diff --git a/src/utils/exam-canvas/model.ts b/src/utils/exam-canvas/model.ts
index 22bdb54..105471c 100644
--- a/src/utils/exam-canvas/model.ts
+++ b/src/utils/exam-canvas/model.ts
@@ -4,6 +4,7 @@ import type { ExamTemplateDetail, TemplateReplacePayload } from '../../types/exa
 export const PAGE_HEIGHT = 1100
 export const PAGE_WIDTH = 780
 export const PAGE_GAP = 0
+export const BOUNDARY_LINE_HEIGHT = 12
 
 export interface CanvasPageGeometry { pageNumber: number; x: number; y: number; w: number; h: number }