Excel Page Width Error

Hi,
I'm often using Excel. But , i can not understand issue that:
I set page size to A4 ( 210 x 297 mm ) . Then i add rectangular which width size is 210 mm to my sheet. Despite rectangular width and page width is same, rectangular is not fit on the page and is overflow on the page.
How can i fix this problem?
Note: Page margins is zero.

Example Page:

Example Page Margin: