OK I've just fixed it, it turns out the css file was in a folder in the public directory which I'd forgotten to reference, so I've just put it straight into the directory. Also the javascript I was trying to use was located inside the body, which I didn't realise as I was using the default layout. So I just moved the javascript to the default layout file.

Phew, thanks for reminding me to check, my mind tends to go blank after coding for a whole day!