Most stuff is the same. It's the same fonts, just using Source Sans Pro more and the type is in general a bit larger. Same organization. Same site sections.
It's on a brand new server over at Media Temple. It's a custom build running PHP 7 with OPCache, MariaDB, nginx-only, SSD hard drives. The site hasn't felt this fast in years, particularly the logged-in, uncached, back-end, database-y stuff. Perhaps most cool: it's HTTP/2 now!
Every mid-article header has a unique ID now. Hover over them to reveal a # link. This way you can link to parts of any article.
Andrew Norcross helped me with a bunch of stuff. High five, Andrew. For example: we got responsive images now working site-wide. That's a native feature of WordPress now, but it wasn't working because of the custom markup I use. Speaking of Andrew, we're also using his Can I Use... shortcode plugin, so I can drop in browser support tables where needed that will stay up to date automatically.
There's a forum thread discussing the design if you care participate in that. There's even a new feature in the forums: if you created a thread, you can mark people's responses as "good answers" if you want to.