I find it very difficult to read the font of the article previews. The article header is fine, but the url and the description text are hard to read. The font looks faded in sections. I guess that is just the font design, but for a Wikpedia Viewer, I would pick a font which is easier to read.
Also, you might consider shrinking the space between the search line, the random article button, and the results section. When my browser was not full screen and I was typing in the search line, I could not see the articles showing up at the very bottom. At first I did not think it was working until I scrolled down the page.
I have to agree … the font used is very bad … even with my reading glasses im struggling to read the text. also when you are typing in the search area the whole page shudders as it loads the articles. but other than that looks fine works well