Your Site Was Built for Two Screen Sizes. Tomorrow Apple Ships One That Changes Mid-Session

Your Site Was Built for Two Screen Sizes. Tomorrow Apple Ships One That Changes Mid-Session

Tomorrow, Wednesday 9 September, Apple holds its annual event at Apple Park under the title Surprise and shine. That is the extent of what the company has officially confirmed: the date, the title and the streaming platforms. What the specialist press expects is a new iPhone generation, and alongside it Apple's first foldable device.

If you run a business, this is not news about a phone you might buy. It matters because a screen is about to open your site and your app and behave in a way you never designed for: its width changes while the customer is in the middle of something.

What Apple confirmed, and what is only reported

The distinction matters before you build any budget decision on it:

• Confirmed by Apple: the event is on Wednesday 9 September 2026 at 10:00 a.m. Pacific Time, from Apple Park, titled Surprise and shine, streamed on Apple's site, YouTube and the Apple TV app.
• Reported, not confirmed: a book-style foldable with an outer display around 5.5 inches and an inner display around 7.8 inches, starting somewhere near two thousand dollars. These are specialist-press estimates, not official figures, and every one of them could change tomorrow.

So do not build a decision on any of those numbers. Only one thing here is worth building on, and it holds regardless of the final specs: a class of screens whose area changes at runtime is now a real part of the market.

The category is not new. Its size is

Foldables have been on sale since 2019 from other manufacturers, but the segment stayed small enough to ignore without consequence. Apple entering it — if tomorrow goes the way the reports say — does not invent the category. It moves it from a margin that never showed up in your analytics to a slice that does.

We are not going to hand you a market-share percentage we have no official source for. The only number that matters is already in your own dashboard: open your analytics and look at what share of your visits come from iOS devices. If it is meaningful, this form factor reaches your numbers in months rather than years. If it is small, the matter is less urgent but it does not go away.

The real change: width shifts inside the session

The web learned long ago to handle different sizes: phone, tablet, desktop. But the silent assumption behind most of what has been built is that the size is settled the moment the page opens and then holds until the session ends. Rotating the device was the rare exception, and plenty of sites handle even that badly.

A foldable breaks the assumption dozens of times a day. The customer opens the device and the viewport jumps from phone width to something close to tablet width, then folds it and it snaps back. Reports say the inner display is wider than it is tall when open, which means the layout you designed for a phone may render into a horizontal space you have never once tested.

One rule covers the consequence: anything in your interface that measures the available space once and then caches the answer will be wrong after the first fold.

Where things actually break

• Layout that reads width once. Code that reads window width on load and locks in a decision — mobile menu or desktop menu — keeps that decision after the unfold until the customer reloads. The sound approach leaves the decision to CSS queries that recalculate on their own, not to a stored variable.
• Device detection from the user agent. Deciding which version of the site to serve based on a device name fails twice over: once because a single device is now two sizes, and once because device lists go stale with every launch.
• State lost on re-render. This is the commercially dangerous one. The customer is halfway through an order form or a payment step, opens the device, the interface rebuilds and the fields empty or the step resets. It never shows up in a static page test, and it shows up immediately in your completion rate.
• Tables, maps and carousels. Components that compute their own dimensions on load are the first to distort: a table that overflows the page, a map stuck at its old size, a carousel frozen mid-transition.
• Your mobile app, if you have one. Both platforms now present multi-window states and shifting sizes. An app that assumes a fixed height and width shows up with empty margins or clipped elements.

Five checks you can run this week without buying a device

You do not need a foldable to find out where you stand. Open your site in a desktop browser and drag the window edge slowly in and out, then watch:

• Does the menu and layout shift smoothly as you drag, or does an old shape stay stuck until you reload?
• Fill in half a contact form or add a product to the cart, then change the window width. Is the data still there?
• Enter the payment step and change the width while you are in it. Do you stay on the step or drop back to the start?
• Open a page with a table, a map or a carousel and change the width. Does it recompute its dimensions, or distort?
• Try an awkward middle width, roughly between 700 and 900 pixels. Most sites are tested at the well-known phone sizes and at desktop, and the band in between is exactly where an unfolded device lives.

That last check alone surfaces most of the problems, and it costs you ten minutes.

The Origami view

We read this as a clean illustration of a rule we repeat to our clients: do not build your interface around a list of devices, build it around the available space. Any design that assumes a specific device starts ageing the day it ships, because every year adds a size that was not on the list. A design that reads the space and rearranges itself needs no edit when a new category appears.

And the checks above are not only about foldables. A site that passes them is sturdier on split windows, car displays, in-branch screens and older browsers. We build on that footing from the start, and we review it on existing sites as part of user experience work. You can reach us on the contact page.

The bottom line

What Apple announces tomorrow is Apple's business. What is yours is that the class of screens whose area changes during use is growing, and that your site most likely rests on the assumption that size settles after load. Drag your window edge for ten minutes today and you will see with your own eyes what your customer sees in a few months. Fixing it while it is small is far cheaper than fixing it after someone calls to say their order vanished halfway through.

Sources

• Apple's official invitation to the 9 September 2026 event titled Surprise and shine, with its date, venue and streaming platforms — as published by MacRumors and 9to5Mac on 26 August 2026.
• Specialist-press reporting on the expected foldable device, including the two display sizes and the starting price — MacRumors and 9to5Mac; estimates Apple has not confirmed.
• The presence of foldable devices on the market since 2019 from other manufacturers — announced manufacturer launch records.