Kagi allows you to provide custom CSS if you want to tweak it to your liking. I've used it to remove some of the widgets I don't personally find useful, and to replace some icons.
A common use case for maximized browser window - tab-bar on the left- or right-side of the browser, and websites set to zoom to more than 125+ % to read it comfortably ... With higher resolution and bigger screen monitors everything seems to be getting tinier and tinier on screen. :)
Yeah my browser and my terminal always share a 60/40 split on a basic 1080p monitor at work. I actually hate having it take full width now. Everything is condensed and is less strain on my eyes.