A short insight into what dangers is lurking around the corner with adoption of Tailwind v4. It will see you haemorrhaging users / visitors if done without forethought and caution.
As some background, with the recent release of Tailwind v4 I was eager to upgrade when the message popped up of a new version. It was an easy update, although the upgrade tool left things breaking, a manual updated based on their guide got us going in no time.
This is where the shock of it came in. Having updated, I was shocked when I did some obligatory testing of our little public SaaS product.
There was certain machines, and browsers that simply does not support Tailwind v4. Due diligence had me installing the latest supported versions of the browsers, trying to do OS updates and boy - that was a waste of time. I ran head first into a wall.
I Googled, and got a bunch of AI slop, but nothing relevant on most of the forums.
Then, I stumbled upon this:
<blockquote>
Tailwind CSS version 4 is considered incompatible with older browsers, as it is designed to leverage modern CSS features and is primarily tested on recent browser versions like Chrome 111, Safari 16.4, and Firefox 128, meaning older browsers may not render Tailwind styles correctly due to missing feature support; developers should be aware of this when using Tailwind 4 and consider potential compatibility issues with older browser users.
</blockquote>
This whole upgrade cycle, this escaped us completely. So finally, we dug up this in their Docs: <a href="https://tailwindcss.com/docs/compatibility" target="_blank" rel="noopener nofollow">https://tailwindcss.com/docs/compatibility</a>
Gee, thanks Tailwind.
Basically on anything older than these browsers, you are out of luck:
<ul>
<li>Chrome 111 (released March 2023)</li>
<li>Safari 16.4 (released March 2023)</li>
<li>Firefox 128 (released July 2024)</li>
</ul>
That is a bummer.
But what about aunt Suzy’s company who use our niche app - everyone at her business uses older Macbooks? She is our biggest client!
Sucks to be you. That is the price to pay for progress.
Sadly the kicker is that half the internet is still on old Operating Systems, and old browsers. Stats are everywhere, have a look at your user base demographics. Running a website? Then ask yourself how many of those people are going to see through the matrix and leave?
It’s a tale as old as CS, with a moral to the story.
Those quick to adopt better have nothing to lose. So please, take it from me - make sure you are OK to upgrade based on your your client hardware.
Honestly, I blindly updated from Tailwind v3 to v4, and realised a lot of our clients won’t be able to use our SaaS product, so be better than me. unless you like a gamble - but don’t say nobody raised a red flag.

Projects die when good developers stand ideally by. 

When Good Projects Die Hard

Upgrading to Tailwind v4 may cause significant compatibility issues with older browsers, as it leverages modern CSS features. Developers need to ensure their clients' hardware and browser versions support Tailwind v4 to avoid losing users, as the latest version is primarily tested on recent browser versions like Chrome 111, Safari 16.4, and Firefox 128.

Tailwind 4: The silent SaaS killer

Thank you for sharing your experience about it.

<h3>Update</h3>
They fixed support in 4.1, thanks for listening to the community Tailwind.
<h3>Announcement</h3>
<img src="https://media.daily.dev/image/upload/s--o0u22spY--/f_auto/v1743748997/ugc/content_ff04fe46-bc91-4380-b9bf-9181f281cbc2" alt="IMG_9696">