Please note that the website is a technical demo of the ferro library and gives some background information about how it works. The intended target audience of the website are web- and software developers. I didn't invest a lot of time in browser compatibility since web developers tend to use newer browsers. Edge 15 is excluded because it doesn't fully support CSS grid. I'm not a very good web designer nor a CSS expert, so the website is a little bit rough around the edges. Please don't shoot the messenger/website.
Ruby's is all about programmer happiness. My intention with ferro is to increase web-developer happiness. What makes me as a web developer unhappy is front-end frameworks (regardless of the language they are written in). Using a front-end framework usually involves a mix of some server-side rendered html, a bunch of code and a templating language. The templating language looks like html but with extra syntax added to connect with the js code. In other words to be able to move application logic from the server to the web browser an even more complex version of html is used. And I need to write in 3 different languages. Very unhappy.
Ferro tries to solve this problem in a different way. By getting rid of html (and thus any links between html and code) and replacing this with code to create a memory structure that fits the application you want to build. The ferro library handles the creation of the necessary DOM elements. The web developer only needs to write in 1 language (apart from CSS). I think that this makes front-end web development much simpler. And me a lot happier.
Some folks mentioned that html is used for tasks it wasn't intended for. I agree, html was originally created as a markup language with some meta data added. Kind of what we use markdown for these days. All sorts of things were bolted on later: styling cues, document structure, semantical elements, js code. It works but it makes separation of responsibilities (structure/content/styling/logic) harder. Internally a web browser doesn't even use html, but only keeps a memory structure we all know as the DOM. Html is one way of telling the web browser what the DOM should look like. For simple web pages that is absolutely fine. For (progressive) web apps html is not ideal.