The background image does not display problem_html/css_WEB-ITnose

I made a login page. When I logged in, everything was normal. But after logging in, when I exited and returned to the login page, the background image of the login page was not displayed. I beg for advice.

Reply to discussion (solution)

Where is the link or code?

No problem. This is the first time I encountered such a problem. The login page is one level above the background page.

Server.Transfer("../index.aspx");

Haha, I have solved it, thank you everyone