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).
* Supports dark mode and/or works with most "dark mode" browser addons
* A good score on Mozilla's HTTP Observatory
* Optimized images. You also might want to use HTML's <picture> element, using jpg/png as a fallback for more efficient formats such as WebP or AVIF. Use tools such as oxipng to optimize images.
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. Beyond basic layout and optionally supporting dark mode, authors should not 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.
### But most users don't change their fonts...
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.
### But wouldn't that allow a website to fingerprint with fonts?
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.
## About lazy loading
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:
