I'm trying to create a "Module:Documentation/styles.css" page (similar to en:Module:Documentation/styles.css) on a new installation of MW 1.37.2 (with Lua 5.1.5), but when I try to save the page I get an error message saying the formatting of the page has unexpected characters. I even tried copying exactly what was in the en:Module:Documentation/styles.css page, but I still get the error. It seems to be treating the CSS as if it's Lua code rather than CSS. Is there an additional extension I need to install to make it treat the CSS as CSS instead of Lua? Or am I missing something else?
Thanks in advance for any assistance.