The comment that points out that this week-long experiment produced nothing more than a non-functional wrapper for Servo (an existing Rust browser) should be at the top:
It’s not just a wrapper for Servo, the linked poster just checked the dependencies in the Cargo file and proclaimed that without checking anything further.
In reality this project does indeed implement a functioning custom JS Engine, Layout engine, painting etc. It does borrow the CSS selectors package from Servo but that’s about it.
In reality while project does indeed have Servo in its dependencies it only uses it for HTML tokenization, CSS selector matching and some low level structures. Javascript parsing and execution, DOM implementation & Layout engine was written from scratch with only one exception - Flexbox and Grid layouts are implemented using Taffy - a Rust layout library.
So while “from scratch” is debatable it is still immensely impressive to be that AI was able to produce something that even just “kinda works” at this scale.