The actual website is based on NextJS, I decided to do on Next because I have never tried it. I also used Tailwind CSS to do styling, with no css code.
Next is a good framework for websites like this. It's easy, it has the pros of React and also additional features for static websites. I also used Gatsby for other website, but I can't say Next is better, because on Gatsby there is a better plugin ecosystem.
So, in this moment (October 2021), I would use Gatsby for a landing website, because it's perfect for my usage and code style.
Tailwind is a good CSS library if you use a component-driven logic, like on React, if you don't use it, it will be difficult to copy all classes on objects. I wouldn't use it for a simple static website written directly on HTML and CSS.
It's very easy to write CSS code with classes like this, I think it's good for simple projects, but maybe it won't be good for important project with super-custom styling, which would need something like Styled Components.
Website is open source, you can find it on Github at this link.
The old website was based on Sapper, the Svelte static website framework created before SvelteKit, now it's not supported anymore. I think Svelte is super when you have to do something simple, or it's been useful also to replace jQuery from code, because is more simple than React, Angular or other frameworks.
I used Tailwind also here, nice, but I didn't use component logic, more difficult and more time-consuming approach, I didn't know which it was also possible on Svelte.
Also this website was open source and you can find it on Github at this link.