Big Black is a blog theme made by PseudoMon. It was designed with two constraints in mind: it should only have two colours, and also its typography should be BIG. I suppose you can call this a "brutalist" web design.

This theme is built entirely with vanilla HTML and CSS. It does use normalize.css and Google Fonts though, and it utilizes a great deal of modern CSS like CSS variable, grid, and overflow-wrap. While it should run well on most people's devices, this site will probably look funny on Internet Explorer.

While it was built for desktop first, this theme is also completely mobile-friendly. If you're on desktop, try changing the browser size. If you're on mobile, try rotating your device.

The HTML files for this theme are written with semantic HTML and using as few superfluous tags as possible. CSS is amazing if you know how to use it right!

For details on how to use this theme, look at its GitHub repository.