I spent two weeks staring at a screen full of horizontal tabs — forty-seven of them crammed into a strip built for an era when people visited ten websites a day. Each tab was a favicon and three clipped letters. That's when it became clear: we'd been building browsers wrong.
The Horizontal Problem
Every major browser treated tabs as a horizontal resource. You get a fixed strip at the top, and when you exceed its width, tabs collapse into unreadable slivers. It's a model broken for people juggling research threads, codebases, and communication tools across dozens of open pages.
The sidebar isn't a feature. It's a quiet rejection of the assumption that every browser should look the same.