Jens Oliver Meiert
Articles and books on the craft of web development, with a focus on HTML and CSS minimization and optimization.
HTML Concepts: Customized Built-In Elements
HTML allows to define custom elements, elements which enable authors to “build their own fully-featured DOM elements.” One special type of custom element is the customized built-in element—a custom element built on an existing HTML element.
Website Optimization Measures, Part XVIII
Random improvements as always, this time covering ARIA roles, Apache module checks, <guid>
elements, CLS rules of thumb, Eleventy, block lists, site licenses, and compression settings.
Conformance and Accessibility
The Web Content Accessibility Guidelines 2.2 are going to obsolete Success Criterion 4.1.1, which had been WCAG’s nod towards conformant HTML output. This is understandable, and it may even be good—to strengthen accessibility as well as conformance.
Speed Up Your Org: When to Require Approval
Organizations can be slow. One thing that makes them slow is process. One part of process consists of approvals. But approvals aren’t always needed. On default answers, and the severity and probability of failure.
My CSSÂ Wishlist
Trim it.
26 Additional Web Development Terms You May Not Have Heard Of
Web Development has its own, special vocabulary that consists of several thousand terms. No one knows all of them. (Or do they?) Here are 26 more terms you may or may not have heard of—perhaps including AAAA or MAM or YMYL.
Challenge Yourself, Even When It’s Art
The paradox of CSS art may suggest an artist had a free pass for the quality of their code. Or does it? I believe there are three possible answers to this.
2022
Release of my next book, a new apartment in downtown Hamburg, good news from the football club, a political adjustment, some travels, and preparation for a professional change—some of my highlights in 2022.
A Problem with Link Relationships
It’s easy to get excited about link relationships and similar types of metadata. But link relationships are invisible information, and some invisible information is notoriously hard to maintain—especially on things that decay, describing attributes that change.
A Brief History of UITest.com
UITest.com just merged with Frontend Dogma, which is asking for select and random screenshots and facts about a site that I ran for 19 years to provide “web-based and free tools for web development and design.”
Website Optimization Measures, Part XVII
Encoding declarations. Conditionals. Ahrefs. ErrorDocument
directives. Mastodon links. Mastodon citizenship. Bitbucket. Eleventy. Action.
The Reverse A-Hole Rule of Social Media
A delayed note about that point at which our defense against disagreeable viewpoints and people becomes an offense.

Upgrade Your HTMLÂ IV
HTML forms the heart of the Web. The beautiful thing is, HTML is easy to learn. Unfortunately, it’s difficult to master. In the Upgrade Your HTML series, I’m taking examples of HTML, discuss these examples, and make them a little better. I’m excited to announce the fourth book of the series.
HTML Concepts: Unstyled Documents
There’s unstyled and there’s fully unstyled. And then there’s also styled “in a manner that is useful for a developer.”
Website Optimization Measures, Part XVI
Spaces, HTTP headers, site generator exports, cite
elements, variable fonts, social logos, no-break spaces, metadata—life is never boring when you run your own websites.
10 Quick Tips for a Great Mastodon Experience
Mastodon is a great alternative to Twitter, feeling refreshingly healthy. Here are 10 things that can help you get off to a great start—from finding a suitable server and interesting people to follow, to useful tooling and mindsets.
Minimal Dark Mode
What’s the easiest and fastest way to set up dark mode? Depending on the setup, something from one declaration to two rules.
Vegan Web Developers
If you’re a vegan and a web developer, why not join us on a humble list of vegan web developers?
Redo Websites Less Often (to Become a Better Developer)
You want to redo websites: The advantages are great, and the ability to put a website on a new foundation is a useful one to acquire. But—you also want to iterate, which means to constantly make small improvements over long periods of time. On how a bias for iteration contributes to becoming a better developer.
HTML 2022: 20 Additional Observations from Analyzing the Web Almanac Data
After the initial analysis for the HTTP Archive’s 2022 Web Almanac, here are 20 more observations about HTML as it’s being used today. From (no) doctypes to conditional comment zombies to verbose form markup to viewports to javascript:
links.
A Short Story of the Google Error Page
Why is the Google error page the way it is? Why is it so plain? What drove development and design decisions? Anecdotes and notes from the time when the page was built.
Website Optimization Measures, Part XV
Automated lossless image compression, mini dark modes, favicon references, prerender
, flat image folders, modest product promotions, compact navigation, theme colors—improvements to my own projects, maybe (or maybe not) of interest to your own.
HTML Concepts: Browsing Contexts
Welcome to another episode of HTML Concepts! Today, browsing contexts—what is that?
0 of the Global Top 100 Websites Use Valid HTML (in 2022)
When you looked at the top websites in 2021, you learned that 98% of them included invalid HTML. When you do the same for the Top 100 globally, this year, would things have improved? Updated data, with a look at our field’s inability to produce valid HTML output.
An Attempt at Outlining the Many Factors Influencing Developer Experience
When looking at DX naively, it can seem that it depends on only one factor—DX = ƒ(x). But Developer Experience depends on many factors, and needs to be approached holistically. A quick attempt at sketching just what factors, each of which can tip the scale.
About Me

I’m Jens, and I’m an engineering lead—currently manager for accessibility at Miro—and author.
In web development, I specialize in HTML and CSS, contribute to technical standards, and write books (like The Little Book of HTML/CSS Frameworks, On Web Development, CSS Optimization Basics, the Upgrade Your HTML series, and The Web Development Glossary).
I love trying things: In philosophy, I’m interested in metaphysics (even in How to Work on Oneself). When it comes to art, I play with photography. And for adventure, I enjoy exploring places (Journey of J.) and activities (100 Things I Learned as an Everyday Adventurer).