ustbhuangyi/better-scroll ? reverse-engineered prompt

Build me a smooth custom scrolling library for mobile web and desktop that works like BetterScroll.

I want it to let me wrap a fixed size container around scrollable content, then handle drag, momentum, bounce, and nested scrolling cleanly, with good performance and no external dependencies. It should feel like native scrolling on touch devices, and still work on PC. Keep the main API simple so I can create a scroller from a wrapper element, and make it easy to add extra features later with plugins, like pull to refresh or pull up to load more, zoom, and moveable content.

Please make the default setup work out of the box, but also support a core only version if someone wants just the basics. If anything is unclear, check the current docs online and match the common behavior people expect from a modern scrolling library.