diff --git a/HFUTCourseSimulation/ImageExport.cs b/HFUTCourseSimulation/ImageExport.cs
index 40bc819..92a129c 100644
--- a/HFUTCourseSimulation/ImageExport.cs
+++ b/HFUTCourseSimulation/ImageExport.cs
@@ -71,8 +71,8 @@ namespace HFUTCourseSimulation {
 
 
                 //draw header
-                graphics.FillRectangle(headerBrush, 0, 0, weekWidth, HeaderCellHeight);
-                graphics.FillRectangle(headerBrush, 0, 0, LeftCellWidth, weekHeight - WeekHeaderHeight);
+                graphics.FillRectangle(headerBrush, 0, 0, weekWidth - Blank, HeaderCellHeight);
+                graphics.FillRectangle(headerBrush, 0, 0, LeftCellWidth, weekHeight - WeekHeaderHeight - Blank);
                 //draw header text
                 for (int j = 0; j < 7; j++) {
                     graphics.DrawString(weekDict[j], textFont, textBrush, LeftCellWidth + j * BodyCellWidth, 0);