What are common reasons for CSS files being sent as HTML instead of CSS in PHP applications?

Common reasons for CSS files being sent as HTML instead of CSS in PHP applications include incorrect file paths in the link tag, incorrect MIME types being set, or the CSS file not being properly loaded. To solve this issue, ensure that the file path in the link tag is correct, set the correct MIME type for CSS files in the header, and make sure the CSS file is being loaded properly.

<?php
header("Content-type: text/css");
?>