In May 2016, most of the Khan Academy site got a redesign (more on that HERE). CS-specific pages were out of scope for the original redesign because they were fundamentally different and more complex than the rest of the site, and in a lot of ways somewhat distinct.
Supporting two different site designs isn't feasible in the long-term though (doing so makes things extra complicated, confuses testing and data, and in general introduces more risk into development), so the CS team is working on updating the CS design as well. Their changes are being gradually rolled out over the next couple of weeks.
I'll be the first one to acknowledge that the original update wasn't exactly universally loved when it came out (here's one such discussion), but there was a ton of great feedback that the team has been reading and making incremental changes in response to (for example, percentages being added back to the Subject menu).
For that reason, if you have any thoughts on this additional update, please post them here! It's always really helpful to hear from everyone.