用php标题渲染css（“Content-type：text / css”）IE问题 - 什么时候？

Question

I am trying to render css with php file:

<?php
header("Content-type: text/css; charset=utf-8");
?>
/*CSS GOES HERE*/

It works fine on my side in all browsers, but I have read some people are having the problem with IE and Edge:

PHP file using content-type: text/css breaks with newest version (13) of Microsoft Edge

header("Content-type: text/css"); is working in Firefox and Chrome, but in Internet Explorer 9 it shows up as 'text/html'

I am trying to reproduce the problem because I need cross browser solution, this code will be used on 100 different sites. But to find solution I need to reproduce the problem first. Under which situation this problem shows up?