Polymer VS marko

Oh, and I know that Wappalyzer detects that Youtube uses Polymer, but here's the thing if you go to the Polymer docs it clearly says "The Polymer library is in maintenance mode. For new development, we recommend Lit."

Polymer - DEAD Recently

It is an open-source JavaScript library based upon Web Components. It is developed by Google. Polymer helps us to create custom elements for building web applications. It's much easier and faster to create custom elements that work like DOM elements.

At least for the YouTube example, if memory serves, they often use Polymer web components for page templating and layout. When you style components through these, oftentimes the CSS styling ends up inline on the page the components are included in.

SolidJS and Tauri form another potent combination for creating performant, lightweight, and secure experiences. SolidJS is a reactive UI library that is similar to Svelte in the way it compiles away reactivity and updates the DOM directly, but it also incorporates a fine-grained reactivity system reminiscent of libraries like Marko, Knockout, and MobX.

Marko is a huge leap in the right direction. It has streaming, partial hydration, a compiler that optimizes your output, and a small runtime. I’ve also heard through the grapevine that Marko V6 also adds resumability to the framework as well.

Nevertheless, the future of JS frameworks is exciting. As we’ve seen from the data, Astro is doing some things right alongside Qwik. However, more noteworthy frameworks such as Marko and Solid are also paving the path forward with some similar traits and better performance benchmarks. We’ve come back full circle in web development - from PHP/Rails to SPAs and now back to SSR. Maybe we just need to break the cycle.

If you want more, take a look on Marko, fresh, qwik or pug. Dind't tested yet but they look like same as Nunjucks.