I think some of the colors of the background and the text aren't really contrasting (I'm talking about the green text and the dark gray background). You can use some color contrast checker tool to choose more appropriate colors. I usually use this tool: https://webaim.org/resources/contrastchecker/ . You may try it if you like And, I think you can enlarge the size of the text a little bit.
P.S. Except for these suggestions, I liked the design of the forum.