You have good eyes :) The screenshot uses the "legacy" white theme that didn't have the flat look yet. It did have a few more dark colors at the edges, which is why it was used for this screenshot. We plan to work with our designer on darker versions of the flat light theme. Until we release those, I can recommend using something like f.lux (https://justgetflux.com/) to make it nicer to work with bright web sites and applications in low-light conditions.