There is a file in /path/to/yournodebb/public called 503.html.
Yes, this is what I meant, sorry !
I have a few questions.
1 is the design of the forums locked to the theme. Adding my custom CSS doesn't seem to work. I am very new to coding so I am sure I have done something wrong. Anyways here is my CSS
2 I saw something about this theme designer plugin that looks awesome but I simply cannot find it anywhere. Has the name changed for it. Is it even still live?
You probably need to be more specific with your rule selector (the 'a' part). If another rule is more specific, it will overwrite yours. Examples:
An 'a' tag with a class: a.someclass
An 'a' tag as the child of a 'div' tag: div > a
An 'a' tag after a tag with an id: #someid + a
If any of such rules exist, they will overwrite yours. You can see what rules are active in most browsers by right-clicking something and choosing 'Inspect'
Other things: Make sure the little checkbox 'Use Custom CSS' below is checked. Try restarting nbb and clearing your browser cache if nothing else works.