Actually, this is my favorite part about Arc. Most of the time when using Arc I'm working in fullscreen mode with 100% of the UI hidden. There is literally zero on my screen except the page itself. If I mouseover to the left (or hit cmd-S) I can see the sidebar/addressbar etc.
It's absolutely wonderful and really puts the focus on the content. I find it much better than how Chrome handles fullscreen.
Cmd+s in Arc just hides all the UI of the browser but does not change the size of the window frame. This is more akin to Chrome's add shortcut to desktop feature, except that it is easy to toggle on/off with a keyboard shortcut. So if you have a web app you want to just focus on, you can just do so.
Incidentally, this is why I love the macOS Safari "Compact Tabs" feature [0] -- this is the most compact browser UI I've come across.
[0] https://www.theverge.com/2021/9/21/22686070/apple-macos-safa...
> For a moment I was mesmerised by its features, how it behaved, and the quirkiness of it.
I think the most important job for a browser is to stay in the background and let the user focus on the website. Chrome does this beautifully. It's elegant, but not eye-catching. It takes up little space for its own UI, and leaves most space to the website.
> At the start, I would use the command bar to quickly make a web search, open a new tab, (try to) launch an existing tab by entering the name of the page, and even perform actions like pinning the current tab.
These are all things you can already do in the addressbar, except for opening a new tab, which is just as easy as opening the command bar.