Safari selected block unexpectedly has default focus outline

[microbit-matt-hillsdon]

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Description

In desktop Safari, the selected block unexpectedly has default focus outline.

I see similar outlines in Firefox too in the keyboard nav demo:

Reproduction steps

1. Use desktop Safari - I used Version 18.5 (20621.2.5.11.8)
2. Drag a block
3. Click on blocks
4. Note weird outline

Stack trace

Screenshots

In demo as built on develop

Screen.Recording.2025-05-27.at.14.17.13.mov

In keyboard nav demo

Firefox:

Safari:

The larger selection outline in Safari seems unrelated, and is in Blockly 11 with Zelos so not a recently introduced issue, ignoring here.

Browsers

Safari desktop