The following applies to minimal websites that focus primarily on text. It does not apply to websites that have a lot of non-textual content. It also does not apply to websites that focus more on generating revenue or pleasing investors than being good websites.
I realize not everybody's going to ditch the Web and switch to Gemini or Gopher today (that'll take, like, a month at the longest). Until that happens, here's a non-exhaustive, highly-opinionated list of best practices for websites that focus primarily on text:
* Final page weight under 50kb without images, and under 200kb with images.
* Works in Lynx, w3m, links (both graphics and text mode), Netsurf, and Dillo
* Works with popular article-extractors (e.g. Readability) and HTML-to-Markdown converters. This is a good way to verify that your site uses simple HTML and works with most non-browser article readers (e.g. ebook converters, PDF exports).
If you really want, you could use serif instead of sans-serif, but serif fonts tend to look worse on low-res monitors. Not every screen's DPI has three digits.
To ship custom fonts is to assert that branding is more important than user choice. That might very well be a reasonable thing to do; branding isn't evil! It isn't *usually* the case for textual websites, though. Beyond basic layout and optionally supporting dark mode, authors generally shouldn't dictate the presentation of their websites; that is the job of the user agent. Most websites are not important enough to look completely different from the rest of the user's system.
A personal example: I set my preferred fonts in my computer's fontconfig settings. Now every website that uses sans-serif will have my preferred font. Sites with sans-serif blend into the users' systems instead of sticking out.
The "users don't know better and need us to make decisions for them" mindset isn't without merits; however, in my opinion, it's overused. Using system fonts doesn't make your website harder to use, but it does make it smaller and stick out less to the subset of users who care enough about fonts to change them. This argument isn't about making software easier for non-technical users; it's about branding by asserting a personal preference.
It's not a good idea to require users to automatically override website stylesheets. Doing so would break websites that use fonts such as Font Awesome to display vector icons. We shouldn't have these users constantly battle with websites the same way that many adblocking/script-blocking users (myself included) already do when there's a better option.
That being said, many users *do* actually override stylesheets. We shouldn't *require* them to do so, but we should keep our pages from breaking in case they do. Pages following this article's advice will probably work perfectly well in these cases without any extra effort.
I don't know much about fingerprinting, except that you can't do font enumeration without JavaScript. Since text-based websites that follow these best-practices don't send requests after the page loads and have no scripts, fingerprinting via font enumeration is a non-issue on those sites.
Other websites can still fingerprint via font enumeration using JavaScript. They don't need to stop at seeing what sans-serif maps to; they can see all the available fonts on a user's system, the user's canvas fingerprint, window dimensions, etc. Some of these can be mitigated with Firefox's "privacy.resistFingerprinting" setting, but that setting also understandably overrides user font preferences.
Ultimately, surveillance self-defense on the web is an arms race full of trade-offs. If you want both privacy and customizability, the web is not the place to look; try Gemini or Gopher instead.
For users on slow connections, lazy loading is often frustrating. I think I can speak for some of these users: mobile data near my home has a number of "dead zones" with abysmal download speeds, and my home's Wi-Fi repeater setup occasionally results in packet loss rates above 60% (!!).
Users on poor connections have better things to do than idly wait for pages to load. They might open multiple links in background tabs to wait for them all to load at once, or switch to another window/app and come back when loading finishes. They might also open links while on a good connection before switching to a poor connection; I know that I often open 10-20 links on Wi-Fi before going out for a walk in a mobile-data dead-zone.
Unfortunately, pages with lazy loading don't finish loading off-screen images in the background. To load this content ahead of time, users need to switch to the loading page and slowly scroll to the bottom to ensure that all the important content appears on-screen and starts loading. Website owners shouldn't expect users to have to jump through these ridiculous hoops.
### Wouldn't this be solved by combining lazy loading with pre-loading/pre-fetching?
A large number of users with poor connections also have capped data, and would prefer that pages don't decide to predictively load many pages ahead-of-time for them. Some go so far as to disable this behavior to avoid data overages. Savvy privacy-conscious users also generally disable pre-loading because they don't have reason to trust that linked content doesn't practice dark patterns like tracking without consent.
Users who click a link *choose* to load a full page. Loading pages that a user hasn't clicked on is making a choice for that user.
### Can't users on poor connections disable images?
I have two responses:
1. If an image isn't essential, you shouldn't include it inline.
2. Yes, users could disable images. That's *their* choice. If your page uses lazy loading, you've effectively (and probably unintentionally) made that choice for a large number of users.
Some users' browsers set default page colors that aren't black-on-white. For instance, Linux users who enable GTK style overrides might default to having white text on a dark background. Websites that explicitly set foreground colors but leave the default background color (or vice-versa) end up being difficult to read. Here's what this page would look like if it messed with the colors carelessly:
