Fixes https://github.com/tailwindlabs/tailwindcss/discussions/15184,
https://github.com/tailwindlabs/tailwindcss/issues/14955
There's a strange bug in Safari < 18 where mixing a color with
`transparent` or with a gray tone, the resulting color looks as if it's
been interpolated through a red-ish color.
Here's the same blue to transparent gradient in Safari 17 using OKLAB
and OKLCH for comparison:
<img width="747" alt="image"
src="https://github.com/user-attachments/assets/1cb09b00-0d84-4284-be34-103726d8af03">
In other browsers, both of these examples look identical.
This bug also shows up when using an opacity modifier right now because
we use `in oklch` in our `color-mix(…)` calls:
<img width="744" alt="image"
src="https://github.com/user-attachments/assets/b029c5f1-0c5c-4119-80ba-dfeabe25927e">
This PR updates all of the affected places in Tailwind to use `in oklab`
instead of `in oklch` which then renders everything as expected in all
browsers.
The big unfortunate change here is changing the default behavior of
gradient utilities like `bg-linear-to-r` to use `in oklab` instead of
`in oklch`. This means you get muddier gradients by default when
creating a gradient between two regular colors (no transparent or gray),
like how they looked in v3:
<img width="740" alt="image"
src="https://github.com/user-attachments/assets/d02e7596-4c99-4ba3-b929-d2db4911c8e9">
This feels worth it though to avoid people getting bitten by this Safari
bug without realizing it, and people can always opt in to using OKLCH
with classes like `bg-linear-to-r/oklch`. The nice thing about making
this opt-in is that no one will opt-in to this when using transparent or
gray because it won't make things look any different/better, and the
only places where it does make things look better _do_ work as expected
in Safari anyways.
---------
Co-authored-by: Adam Wathan <4323180+adamwathan@users.noreply.github.com>
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