Thanks for reporting as @pkiller mentioned this should be fixed if you create the system folder. I have also fixed it on master as well as the error messages so you should get a better error message if the upload fails.
Trying to get forums design customized.
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.