In sheet1，I select the row 10 to insert a row；
In sheet2，I select the row 9 to insert a row；
cell border style changed differently。

In sheet1，I select the row 9 to set top border and bottom boder；
In sheet2，I select the row 9 and row 10 to set top boder；

Different operations cause different border changes.


What are the special border changing rules when inserting rows or columns in excel?

border.xlsx