New task button selected highlight is not consistent with others across OS

## What Happened

When selecting a new task and then leaving, the highlight around it is not the same as other button highlights. It has square corners and the padding is not centered. Compare that to the highlight around "+ Add Task List..." button, which looks right except for the fact that it's gray instead of my accent color or pink for Tasks' accent color. Photos to show.

highlight around the + button in printer settings which is rounded, well padded and uses my accent color.

## Expected Behavior

That the highlight would be the same as others across OS.

## Steps to Reproduce

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### Logs

## Platform Information

elementary OS 6 Odin