Mermaid diagrams render labels incorrectly when using Safari

Description

Labels in Mermaid diagrams render incorrectly in the Collectives app when using Safari.
The diagram shapes and arrows render correctly, but all text labels (node labels and edge labels) are shifted to the top of the diagram and overlap each other, making them unreadable.

Occurence details
The issue occurs in Safari 18.6 on macOS when using Nextcloud 32.0.6 with Collectives 3.6.1.
It does not occur in Firefox 146.0.1 on the same system.
It also does not occur in Safari for Nextcloud version 30.0.16.

Additional information
This issue was previously described (including screenshots) in the Nextcloud forum: Mermaid does no longer render correctly in collectives
The forum thread was automatically closed after 90 days without resolution, and the issue still persists.

I hope this issue is reported with sufficient information in the correct repository now. If not, I apologize and would appreciate guidance on where it should be filed instead.

To Reproduce

Use Safari on macOS!

1. Go to any Collective page
2. Insert a Mermaid code block, for example:

graph TD
    A[Start] --> B[Process]
    B --> C[End]

3. Observe the rendered version of the diagram either as preview or after saving the page.

Current behaviour
In Safari, the diagram labels overlap at the top of the diagram and are unreadable.

Expected behavior
Mermaid diagrams should render with correctly positioned labels in Safari, as they do in Firefox 146.0.1 and in Nextcloud 30.0.16.
(GitHub also renders it correctly in Safari on macOS)

graph TD
    A[Start] --> B[Process]
    B --> C[End]

Screenshot

Further details

Server details
Collectives app version: 3.6.1
Nextcloud version: 32.0.6
PHP Version: 8.3.30
Database: MySQL 10.11.14
Hosting type: Managed hosting

Client details
OS: macOS
Browser: Safari
Browser version: 18.6
Device: Desktop

No source file or test is named. First reproduce the Mermaid example in Safari 18.6 on macOS and compare it with Firefox and the listed Nextcloud versions; then trace the Collectives Mermaid rendering path. Done means labels are positioned correctly in Safari without regressing the working cases.