[Bug]: Collapsible can't be nested - Worked in 1.0.0

[KajKandler]

Before submitting...

• I have searched for duplicate or closed issues.
• I have read the CONTRIBUTING document and my issue is following the guidelines.
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Context

Set up a nested collapsible like in https://github.com/KajKandler/ce-sidepanel-colapsible-test/blob/main/sidepanel.html

Current Behavior

When opening the Collapsible "2." and some of its siblings "2.1" ... The collapsible body does not expand to contain the larger height elements.

Expected behavior

The box expands and pushes down the rest of the content

Possible Solutions or Causes

I did not compare the code between the versions or triaged which version introduced the bug.

Steps to reproduce

What steps will reproduce the problem?
(1) Checkout the project at https://github.com/KajKandler/ce-sidepanel-colapsible-test
(2) Open the sidepanel.html with a live server (Visual Code)
(3) Open "2."; Then "2.1.", then "2.2."
(4) Close and re-open "2."

Your Environment

• Version used: 2.1.0
• Browser Name and version: Chrome 128.0.6613.115 (Official Build) (arm64)
• Operating System and version (desktop or mobile): MacOS 14.16.1 desktop
• Additional information you want to tell us: