PHP input in the address bar, leading to invalid CSS styles. how to redirect to a specified page-php Tutorial

PHP input in the address bar, leading to invalid CSS styles. how can I redirect to a specified page? for example: www.test.com/test.php, if I enter it in the address bar, the result of www.test.com/test.php/sdfsdf/klklj leads to test. php CSS style invalid. please advise me how to jump to an error handling page, such as www.test.com/error.php

Reply to discussion (solution)

Pseudo-static, non-compliant URLs can jump to the custom 404 page
I wonder why the csssu style you mentioned is invalid.
Are other data displayed normally on the page?

Reference css with relative root directory path or absolute path

Reference css with relative root directory path or absolute path
+ 1

Thank you !!!
Thank you!
This problem will not occur if css is referenced in the absolute path.