CodeByZach/pace ? reverse-engineered prompt

Build me a tiny library I can drop into a website that automatically shows a progress bar while the page is loading. It should start as early as possible, watch normal page load, ajax requests, and any long running javascript, then hide itself when the page is ready.

I want it to be easy to use, just include one script and one theme css file and it works right away. Please also make it support a few simple settings, like turning ajax tracking on or off, restarting when navigation changes, ignoring certain requests, and adding custom selectors to wait for. It would be great if I can choose from a few different bar styles with css themes, and also add my own class names for small visual tweaks.

If there are any details you need from the latest docs or browser support notes, look them up online and match the existing behavior as closely as possible.