Was this ever fixed as I can see my css gets the response code 200 but it delvers as txt/html and this results in it not being loaded. Interestingly, when you look at the page source and you click on the html it resolves it like a web page and loads another redirect web page. Any clue how to go by this?
Ask yourself why you need separate css files for a simple splash page.
If you still do, read my workaround of 21st May in #46
"If you are trying to do something much more sophisticated you would be better of using the uhttpd already running on OpenWrt. This is by default not accessible to clients when at the preauth stage. You need to allow access by adding an entry into nodogsplash.conf
With your css files under /www/mycss/bootstrap.min.css, add the following line to nodogsplash.conf:
FirewallRule allow tcp port 80 to [ipaddress_openwrt]
You do not need libevhtp libneon or libmicrohttpd .