Jen Simmons

 Apple Evangelist on the Web Developer Experience team for Safari & WebKit (npub1k5x…df3x). Member of CSS Working Group. Formerly Firefox. #longCOVID since March 2020. #pwME

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Github: https://github.com/jensimmons
CodePen: https://codepen.io/jensimmons

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Last Notes

2025-12-20 00:22:54 GMT

Did you see everything in Safari Technology Preview 234?
https://webkit.org/blog/17674/release-notes-for-safari-technology-preview-234/
It’s got a lot of new features including Grid Lanes, Threaded Scroll-driven Animations, seven new Web API, and more. Plus a TON of other improvements & fixes.

2025-12-19 21:33:54 GMT

Have you been wishing masonry layouts would just hurry up and arrive in CSS?? Well, happy holidays!
https://webkit.org/blog/17660/introducing-css-grid-lanes/

2025-11-05 20:19:55 GMT

Curious about web technology coming to Safari? How about `field-sizing`, `position-visibility`, `random()`, `scrollbar-color`, `hidden=until-found`, auto-expanding `<details>`, `command` & `commandfor`, Largest Contentful Paint, CHIPS, `scrollend` event, Navigation API & much MUCH more!
https://developer.apple.com/documentation/safari-release-notes/safari-26_2-release-notes

2025-09-30 20:41:54 GMT

I’m surprised I haven’t heard more responses from web developers about the change to Safari on iOS and iPadOS regarding web apps. Now every website can be a web app (saved to the Home Screen and opened as a stand-alone app) — not just sites that have been configured a certain way by the developers.
It’s a big difference for users. Every site gets the same experience. No more mysterious sometimes-it-works-one-way, sometimes-another.
Read more: https://webkit.org/blog/17333/webkit-features-in-safari-26-0/#every-site-can-be-a-web-app-on-ios-and-ipados
https://cdn.masto.host/frontendsocial/media_attachments/files/115/295/174/161/616/221/original/5e9f5a58794e7fc0.png

2025-09-15 16:52:05 GMT

Have you been meaning to learn how to use CSS Subgrid? Here’s a very practical and straightforward how-to from @saron.bsky.social!
https://webkit.org/blog/17339/subgrid-how-to-line-up-elements-to-your-hearts-content/

2025-09-04 06:30:58 GMT

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So, I'll just post this one thread. Because it's everywhere right now.
Do I dare beg you to care again? Quote the science / find all the links to proof? I don't know. I need to sleep & probably it won't matter. The facts are easily found. Most are already known by most people.
This is a problem of empathy now. To wake up (yes) and recognize that "but I'm a good person, so I don't have to worry, it won't get me, I have good health/genes/morality" is eugenics.
Choose another path.
Please?

2025-09-04 06:27:15 GMT

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I learned about Covid in Jan 2020, and looked up a LOT of information in Feb. What I learned alarmed me, so I prepared (long before most people in the U.S. did) and then I spread the news on Twitter. [RIP, I miss Twitter.]
I wrote a lot about Covid in 2020 and 2021 on Twitter.
And then I gave up. I realized the people around me did not care. And I was screaming into the wind.
But sadly Covid did not let go of me. I'm still disabled by it. Every day.

2025-09-04 06:24:24 GMT

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We know a lot about this virus. We know how to take care of ourselves & each other.
You just have to decide that you want to.
It was incredible in 2020 to see how much people cared, & how far they were willing to go to help their neighbors, friends & family.
It was devastating to watch in 2022 as 98% of people decided that they were done caring. And instead choose delusion. To intentionally infect others rather than experience more inconvenience.
It's not too late to start caring again.

2025-09-04 06:19:34 GMT

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Waste water data from cities in the United States are showing a massive outbreak in many places right now. I'm watching one person after another get it. While almost no one is taking precautions.
The information we were told at the beginning about it not infecting or affecting kids much turned out to be proven by scientists to be wrong. Kids do suffer horrible consequences.
Masks make a massive difference. You need masks that seal, KN95 or N95. Covid is airborne. It floats far.

2025-09-04 06:15:57 GMT

Covid is highly contagious.
It’s airborne. Floats in the air & hangs for hours, like measles. You can show up later & get infected.
It’s incredibly damaging to the human body. Especially if you are infected over & over.
The vaccines are amazing. And yet, they do not prevent vaccinated people from being infected & contagious.
Many infectious people have no symptoms at all.
The rapid home tests have an incredibly high rate of false negatives. A negative test does NOT mean you don't have it.

2025-09-03 21:35:56 GMT

Web developers,
I have a question for you. Imagine an idea for a new web technology is proposed. But at least of the browser makers formally objects because of privacy concerns or other reasons. They say "No, we object to this proposal. We will never ship this. Let’s redesign it without these problems." But the other browser disagrees & ships anyway.
Should that technology be considered A Web Standard — when 1 or 2 browsers implement & ship, while 1 or 2 browsers Formally Object and say no?

2025-08-06 23:19:39 GMT

Web developers, do you test your sites in Safari Beta? (On a standalone machine, automated? On your Mac?)
If not, why? Is it because installing the beta overrides regular Safari? If you could have Safari & Safari beta both at the same time, would you do so?
What do you need? Why? Share details!

2025-08-05 17:36:25 GMT

Over the years, I’ve heard a lot of developers & other people wish that uBlock Origin was available for Safari. Now it is! Download for Safari 18.6 and Safari 26 beta.
https://apps.apple.com/app/ublock-origin-lite/id6745342698

2025-07-25 17:20:37 GMT

What do you need most from WebKit (the rendering engine for Safari that runs your HTML, CSS, JS, and more)?
If you are making websites, what could we do in WebKit to make it easier for you to create fantastic experiences for your users?

2025-06-24 16:59:38 GMT

Imagine one group advocates for a new web technology, and write down their ideas. And then other people have concerns about those ideas (maybe thinking it’s not well designed, not easy for developers to use, invades privacy, isn’t secure, etc)… so they are totally not on board. If those ideas end up in a web standards group anyway, and get pushed through while the original group still objects — is that a web standard or not? If a browser formally objects & refuses to ship, is it a web standard?

2025-06-16 02:17:14 GMT

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A ban on masks is a ban against people like me existing in public. I got covid before the lockdowns in the U.S., because our government failed to act. It left me significantly disabled. And now, I must avoid getting it again. A mask ban is a return of the ugly laws, a ban on disabled people. I will not obey. Let’s go to court. Absolutely not. I have a right to exist.

2025-06-11 20:23:47 GMT

Now that you’ve seen what’s coming in Safari 26… web designers & developers, what do you need most to come next? If you were setting the priorities for what happens, what would you put at the top of the list?

2025-05-14 21:52:58 GMT

If you make websites — as a developer, designer, product owner or more — what’s your favorite way to learn about what’s new on the web?
What type of content do you find most helpful?
Where are some of your favorite resources?
What’s hard? What doesn’t work? Why?
What do you need that you don’t have now?
What do you want to learn? What could unblock you?
If you could wave a magic wand, what would you want someone to make for you???

2025-05-13 19:00:30 GMT

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Oh, this is what I was talking about. It started with a quick demo on CodePen to check out what `contrast-color` does. Then a very short blog post for that demo. Then… oh.
Now it’s a 2500 word article on contrast algorithms, questioning how best to get to true accessibility…
https://webkit.org/blog/16929/contrast-color/

2025-05-13 18:50:11 GMT

Have you ever wished the browser would look at a background color and pick black or white for the text — whichever one provides more contrast? Now, the `constrast-color()` function in CSS does just that.
https://webkit.org/blog/16929/contrast-color/

2025-05-09 00:49:54 GMT

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This is one thing I love about what I do. I get to find out so many things I would never had known, because I'm surrounded by smart & generous experts who chime in and make the content we are preparing for you much better. The bar is really high, and we keep perfecting things over and over until they are right.
I'm excited about what I learned. I'm proud of what I'm getting to write.
The work is far better than what I could ever do alone because of my colleagues.

2025-05-09 00:39:55 GMT

Hey, let me write about this new CSS property, I said. It'll be easy, I said. It's such a simply property… oh wait, what? Why does this demo not seem to work? Oh it does work. But the thing underneath it is flawed? Everyone agrees it needs to be better. People have been working on it for YEARS? Oh. Ok I'll explain that. And just get a few people to review this… wait, what else? Ok add an entire new section. Oh. Rewrite all this?
Weeks later…
Ok, I'll rewrite this whole section again… And this…

2025-05-07 13:08:50 GMT

Using the color picker in HTML for your website? Did you realize it’s been limited to sRGB? Well, no longer. In Safari, now you can use two new attributes to support P3 color and alpha transparency. https://webkit.org/blog/16900/p3-and-alpha-color-pickers/

2025-05-02 16:50:21 GMT

If you write code to make websites (HTML, CSS, JS, Web API, Media files, etc), and you get frustrated trying to wrangle your code to work in Safari, which bugs are blocking you? Which existing features would you most like to see improved? If you got a chance to order priorities, what bug fixing effort would you put at the top of the list?

2025-04-28 20:05:03 GMT

Does anyone have any example of websites that are using SVG for their icons?
Just plain icons? Does anyone make responsive icons? Light/dark icons?
How important is this to you? Would you rely on it if it were more deeply supported?

2025-04-25 16:01:04 GMT

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You can use line-height units (`lh and 'rlh`) in your designs to better tie layout to your typography. Including using them as paragraph margins (instead of `em`) to easily establish much better vertical rhythm. These units are supported in all browsers today!
https://webkit.org/blog/16831/line-height-units/

2025-04-25 15:59:23 GMT

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The CSS shape() function makes it possible to create any shape you want, including custom curves, when defining a shape value for `clip-path`, `offset-path`, or `shape-outside`. And it’s easily responsive, unlike SVG.
https://webkit.org/blog/16794/the-css-shape-function/

2025-04-25 15:57:36 GMT

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`text-wrap: pretty` lets you ask the browser to use a better mechanism for determining when to wrap text, avoiding short last lines, avoiding poor hyphenation, and making the inline end edge less raggedy (improving rag). In Safari, it improves *all* lines of text.
https://webkit.org/blog/16547/better-typography-with-text-wrap-pretty/

2025-04-25 15:54:58 GMT

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Safari 18.4 contains a huge number of new features for web developers, including Declarative Web Push, shape(), sideways writing modes, text-auto-space, P3 support for color pickers, preset device sizes in Responsive Design Mode, and 78 more features!
https://webkit.org/blog/16574/webkit-features-in-safari-18-4/

2025-04-25 15:52:25 GMT

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Item Flow — we came up with a proposal for new CSS that combines `flex-flow` and `grid-autoflow` into a new property called `item-flow`. It allows for new features in Flexbox and Grid, including `item-pack: collapse` for triggering masonry-style layouts.
https://webkit.org/blog/16587/item-flow-part-1-a-new-unified-concept-for-layout/

2025-04-25 15:33:28 GMT

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In case you missed these 6 articles, let me list them… Declarative Web Push — we’ve created a new web standard for push notifications that’s easier to use than the original Web Push. Use declarative JSON formatted a certain way & be done. No need for a Service Worker.
https://webkit.org/blog/16535/meet-declarative-web-push/

2025-04-25 15:23:12 GMT

Make websites? Are you reading webkit.org? We published 6 articles in the last 5 weeks — aiming for at least one a week from now on. Teaching you all about new technology, proposals for the future, and what’s coming in Safari.
• lh units
• shape()
• text-wrap: pretty
• Safari 18.4
• Item Flow
• Declarative Web Push
Plus release notes for Safari Technology Preview every other week.
What should we write about next?

2025-03-28 23:02:08 GMT

Are you excited for masonry layouts in CSS? Wondering what’s happening?
Well, a third option is emerging. One that unifies the `flex-flow` and `grid-auto-flow` properties into a whole new mechanism — Item Flow.
Learn what it is, and what it means for Flexbox and Grid in https://webkit.org/blog/16587/item-flow-part-1-a-new-unified-concept-for-layout/
https://cdn.masto.host/frontendsocial/media_attachments/files/114/242/546/831/198/008/original/1883e87913301dc8.jpg

2025-03-27 18:13:35 GMT

Web Push is exciting. But it requires service workers and a bunch of custom code that can be different from project to project.
How about instead we standardize on using JSON & leave JavaScript out of it!
Meet Declarative Web Push. Available in iOS and iPadOS 18.4 beta.
https://webkit.org/blog/16535/meet-declarative-web-push/

2025-03-21 23:27:48 GMT

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Standards-first is truly important. People have had ideas of how form controls and their custom styling should work for THIRTY YEARS. There is no lack of ideas. What's been lacking is consensus on how to move forward. Anyone pushing a one-company / one-person agenda without true cross-browser, cross-working-group consensus is not going to break the three-decade old log jam.

2025-03-21 22:00:56 GMT

There it is! Finally, a real solution for how to style all of the HTML form controls using your own custom CSS to change anything — building on an interoperable UA set of defaults. It only took 30 years!
First will be the chance to style the “in-page” controls (the part embedded in the webpage), plus the popover for <select> (the part that appears “over top of” the page). Later we’ll do popovers for more things — like the date picker, etc.
Read about it here: https://drafts.csswg.org/css-forms/
https://cdn.masto.host/frontendsocial/media_attachments/files/114/202/668/590/283/062/original/bf5eef679ce9c4be.png

2025-03-17 19:12:59 GMT

Safari Technology Preview 215 is here! It includes several exciting features:
- Scroll Driven Animations
- text-wrap-style: pretty
- CSS Anchor Positioning
- HDR images
- Trusted Types
- File System WritableStream API
https://webkit.org/blog/16523/release-notes-for-safari-technology-preview-215/

2025-03-05 17:43:11 GMT

Styling HTML form controls is something web designers & developers have wanted for years!
My team is working on a solution — you’ll apply `appearance: base` and switch to a new interoperable, consistent controls with easy to override default CSS. They inherit much more of what you already have going on. And then you can override (even more of) those styles using new pseudo-elements.
See the details at: https://drafts.csswg.org/css-forms/

2025-02-21 21:51:08 GMT

We heard your requests!
Responsive Design Mode in Safari 18.4 beta now has a dropdown of preset viewport sizes available. Along with a button to switch orientation.
https://cdn.masto.host/frontendsocial/media_attachments/files/114/044/085/642/442/150/original/2acfe119adda1789.png

2025-01-14 21:41:57 GMT

Interop 2024 reached an all time high interoperability score! Every browser tested earned a 99 while overall interoperability reached 97% pass rate (in preview browsers).
Read more about the success of Interop 2024:
https://webkit.org/blog/16413/the-success-of-interop-2024/

2024-12-11 18:35:30 GMT

Safari 18.2 is here! For web developers, it’s the biggest release of new features this year. Highlights include cross-document View Transitions, text-box, spatial videos in visionOS, ruby improvements, WASM garbage collection, HTTPS by default, Genmoji, and more.
https://webkit.org/blog/16301/webkit-features-in-safari-18-2/
https://cdn.masto.host/frontendsocial/media_attachments/files/113/635/643/020/773/521/original/49858d78537e40b7.png

2024-11-01 20:50:22 GMT

I’m excited about what we have coming in Safari 18.2 for web designers and developers.
- `text-box-edge`, `text-box-trim`, and `text-box`
- cross-document View Transitions, View Transition Classes, View Transition Types, `view-transition-name: auto`
- dividing by numbers with units in `calc()`
- `background-clip: border-area`
- `scrollbar-width` and `scrollbar-gutter`
- ruby-align, ruby-overhang, unprefixed `ruby-position`
- `input type=week` on iOS
And a LOT more!
https://developer.apple.com/documentation/safari-release-notes/safari-18_2-release-notes

2024-10-30 18:17:34 GMT

This article by @npub18q5…ah6v is fantastic. It explores the choice of adding masonry-layout capabilities to CSS Grid vs creating a whole new display type. He created several examples, going through the code needed to create layout variations at breakpoints while still supporting older browsers. What would it be like to use each in the real world?
A highly recommended read!
https://ishadeed.com/article/css-grid-masonry/
https://cdn.masto.host/frontendsocial/media_attachments/files/113/397/730/888/157/745/original/a9f917bb4cd7c54d.png

2024-10-22 20:53:05 GMT

This week is the WebKit Contributor’s meeting — with the browser engineers who contribute to WebKit. Including from Apple, Igalia, Sony, Redhat & more.
Did you know that WebKit is not just the browser engine for Safari — but for many other browsers, apps, and platforms as well? Igalia @npub12wy…lm9d maintains two of them: WebKitGTK @npub1req…6fnv and WPE @npub1kyk…g5gg
WebKit is especially great for devices that don’t have a lot of power. It’s used for digital signs, medical devices, game consoles and more!

2024-10-21 18:43:55 GMT

I’m really proud of this article on Masonry & CSS.
It was incredibly hard to write. We spent weeks writing and rewriting, digging deeper & deeper into the issues at had, working to make things as easy to understand as possible.
https://webkit.org/blog/16026/css-masonry-syntax/
There’s also a really cool idea about how to add another new feature to CSS Grid. (It would make it super easy to create a common article layout that’s not easy today.)
I can’t wait to hear what you think.
https://cdn.masto.host/frontendsocial/media_attachments/files/113/346/884/852/808/022/original/f33bba8bec4da22f.jpg

2024-10-21 18:31:27 GMT

Would you like to be able to create masonry-style layouts in CSS??? We just wrote a giant article with all the latest news on where this feature is at.
The CSSWG is now debating how the syntax should work. Please read our thoughts, and chime in with yours (read to the end of the article to learn how).
https://webkit.org/blog/16026/css-masonry-syntax/

2024-10-17 17:14:33 GMT

If you write CSS (aka typidy-type CSS selectors, properties & values into a code editor), have you learned CSS Grid yet?
If not, reply with why. Why haven't you learned Grid yet? What would cause you to learn it? What help would help?

2024-09-19 14:50:44 GMT

Web developers,
What existing CSS do you struggle with most?
Can you think of an older feature from CSS2/ CSS3, that has been in all browsers for a long time, but still doesn't work the same cross-browser. And so you fight with it, you have to use a hack or workaround. Or you just cannot use that feature at all. Perhaps you haven't even thought about it in a long time because you wrote it off as unusable long ago.
Is there anything that still falls into that category?
What do you want fixed?

2024-09-17 16:38:54 GMT

Safari 18.0 is here. Have you seen what’s new for web development? Lots of new CSS, HTML, JS, Web API, media… Plus new Safari features like Distraction Control, Viewer, and a way to use Safari’s web developer tools with iPhone Mirroring.
Our articles are packed with practical examples demonstrating how to use the new web technology. I hope you find it helpful.
https://webkit.org/blog/15865/webkit-features-in-safari-18-0/

2024-08-18 00:21:46 GMT

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I don’t know which is more shocking — learning that humans are this deeply selfish. That many people I know have the capacity to commit casual murder.
Or to watch communities I used to be a big part of drop me so completely. Discard people like me. Reject us. Banish us. Pretend like I never existed, never contributed anything.
Either way, their every action, every superspreader party, every “yes I’m infected but I need to have a life”… they let me know there is no place in their world for me.

2024-08-18 00:15:36 GMT

Day 1628. It’s still shocking to watch people I used to think were my friends & community ignore the very real danger of the raging pandemic. People *knowingly infected* going about their lives in public, in the park, on airplanes… Basically expressing eugenics in real time. Knowing their actions will kill & disable others, but truly not caring. At all. Even when they know me — are looking right at me — choosing to act in a way that could steal my life away from me. Pretending they aren’t.

2024-06-23 15:30:50 GMT

If you have experience designing and/or coding typography in CSS for the web, what do you find most annoying? What’s hard to do? What’s impossible?

2024-06-13 23:55:05 GMT

A mask ban will ban me completely from indoor public life.
I’ve already been pushed most of the way out of society. I cannot believe people are legislating pushing people like me all the way out. Oh, wait, yes I can. This is what the last 2.8 years have been like. Watching everyone around me deciding one by one they would rather banish me from society than be even the slightest bit inconvenienced. Letting me know their feelings are far more important than my life.
https://med-mastodon.com/@luckytran/112611073769629423

2024-06-04 22:05:38 GMT

If you notice a website that seems broken in Safari, but not in other browsers, please file a report at https://webcompat.com.