Really cool, isn’t it?
It’s the 3D inspector tool in Firefox. I can’t believe I’ve never even noticed it before! Find it here: Menu > Tool > Web Developer > Inspector > 3D (click the “cube” icon). Images below just give you an idea on where to find them in the interface.
Honestly, I’ve never even thought that web page structure can be presented in such a beautiful way. It’s easy to get stuck in some ideas, but when you step back and rethink, there are really tons of other ways to make things better.
Check it out!