Yes, we've deliberately tried to make use of existing libraries (either from other browser engines or general purpose libraries) where possible.

The main thing we pull in from Servo (which is also shared with Firefox) is the Stylo CSS engine, which is a really fantastic piece of software (although underdocumented - a situtation I am trying to improve). I was recently able to add support for CSS transitions and animations to Blitz in ~2 days because Stylo supports most of the functionality out of the box.

(the other smaller thing we use from servo is html5ever: the html5/xhtml parser)

We also rely on large parts of the general Rust crate ecosystem: wgpu/vello for rendering (although we now have an abstraction and have added additional Skia and CPU backends), winit for windowing/input, reqwest/hyper/tokio for HTTP, icu4x for unicode, fontations/harfrust for low-level font operations, etc.

And while we're building the layout engine ourselves, we're building it as two independently usable libraries: Taffy for box-level layout (development mostly driven by Blitz but used by Zed and Bevy amongst others), and Parley for text/inline-level layout (a joint effort with the Linebender open source collective).

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I wish that the Servo project of 2025 was interested in making more of their components available as independent libraries though. Almost all of the independently usable libraries were split out when it was still a Mozilla project. And efforts I have made to try and get Servo developers to collaborate on shared layout/text/font modules have been in vain.