auto_prepend_file deletes first line of apended file

Question

When using php.ini with

auto_prepend_file=/homepages/xyz/htdocs/somefile.php

on the file thickbox.css (for some reasons I have to process css files as php), the first line gets deleted. The beginning of thickbox.css is

#TB_overlay {
    background: #000;
    opacity: 0.7;
    filter: alpha(opacity=70);
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 100050; /* Above DFW. */
}

but the output with a prepended file is

    background: #000;
    opacity: 0.7;
    filter: alpha(opacity=70);
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 100050; /* Above DFW. */
}

The first line is gone!

When I just place a blank before the # or a linebreak, the line reappear. But as soon as the first character is a # the first line is gone.

How can I prevent this?

Answer 1

I found the solution myself. The requested css-file should not just be appended. Instead the 'somefile.php' should output the requested file itself with the following lines at the end:

readfile($_SERVER['SCRIPT_FILENAME']); // the requested file
exit(0);