That was one of the primary reasons I used Opera.
That and the "hide images" button (it worked instantaneously, without the need of reloading the page), also the "invert colours" option, also the zoom (this was way before Opera 12 though, at that time other browsers didn't even have the zoom function).
However, you could try Vivaldi, it has the same skin layout of the old Opera: in the bottom bar (right beside the "hide/show images" button) there's a button with which you can do some CSS customization like invert colours, greyscale, sepia, (there isn't a "fit to width", but the program is still in beta).
It also seems pointless in the modern web with the advent of responsive design.
Sure, responsive design works flawlessly, the usual result that I get when zooming in is that menu elements or other boxes get so bloated that they cover the text below, at that point I'm forced to reduce the zoom to being able to actually read the site.