Curse did around a year ago to unify the brand under the purple twitch theme. This website is broken super badly especially on mobile devices which i use to browse curse.
We're currently working on the new CurseForge client Ux/Ui. You can view some of the design in our roadmap over here.
For the website, we haven't started the design changes, however we plan to have it resemble the client interface. When we start this step, which will only begin after we have a stable client version up and going, we will also take into consideration mobile viewing and exploration.