Check that this is really a bug

• I confirm

Reproduction link

https://codesandbox.io/p/sandbox/jvshjs

Bug description

slidesOffsetBefore and slidesOffsetAfert doesn't work when cssMode is enabled

Expected Behavior

Can be two expected behavior:

• This is the correct behavior, so the doc should be updated to explain this in cssMode incompatibilites
• Is a bug, and should be fixed

Actual Behavior

Doesn't add the space indicated

Swiper version

11.2.5

Platform/Target and Browser Versions

macOS 15.3.1 Firefox 136.0.1

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