Spacing becomes broken when slide's `transition` properties are set to a variable that is not defined during load

[rptfrg]

Check that this is really a bug

• I confirm

Reproduction link

https://codesandbox.io/p/sandbox/swiper-navigation-forked-slrjkk

Bug description

Spacing becomes broken when slide's transition properties are set to a variable that is not defined during load.

How to reproduce:

1. Set spaceBetween
2. Set slide's transition CSS property to any variable, for example var(--animation)
3. Make sure that variable is not immediately defined. It may be defined later on in a separate <style> block. (see the attached reproduction link)
4. Scroll the slider to the end and notice that spacing is broken. (you will see what I mean)

Expected Behavior

Actual Behavior

Swiper version

12.0.3

Platform/Target and Browser Versions

Any browser

Validations

• Follow our Code of Conduct
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.
• Make sure this is a Swiper issue and not a framework-specific issue

Would you like to open a PR for this bug?

• I'm willing to open a PR