As of the time of writing this, this website ships with a minimal CSS page so that it does not look too ugly. However, I wish that this was not required.
Nowadays, most people use CSS to customize their website's appearance, often to convey their brand or express themselves. The downside for the users is that their browsing experience is inconsistent. Websites present their information in different ways and have different themes. At best this is distracting and at worst it can be confusing and annoying. For example, many dark theme users know the pain of having a white page blind them at night.
One solution to this problem is to use a solution like Stylus, which allows users to override specific websites' CSS styles. Unfortunately, the vast majority of websites are not supported and users have to find and setup a new theme for each website.
Another solution would be to override all CSS styles with something custom. In practice, this is even worse as it will break most of the more complex websites, making them unusable. A milder solution would be to only apply a custom CSS style on websites that don't have any. Unfortunately, these are rather uncommon but most importantly, this requires user involvement. As an author, I can't simply not style my website, hoping that my users will do it, since most won't and will then find it ugly to unreadable.
Ideally, websites that use HTML as a document markup language rather than a canvas would simply use the Gopher protocol, which doesn't support server-side styling. Instead, the clients are responsible for theming all pages. This results in a very coherent and pleasing experience. It also means that clients can be as simple or complex as the users want them to be without concessions for the author.
Obviously, none of this is a concern for the vast majority of users. If anything, sites are getting more custom, non-standard and complicated. There is very little demand for document websites so there will never be enough traction to change the status quo by setting a new standard for document websites or by pushing for a more consistent experience for the Web in general. Ultimately, it doesn't matter that much for anyone that different websites are displayed with odd fonts, colors or layouts, but it is interesting and a little sad to see how poor the support for documents is given how big and popular the Web has become.