Layout header top custom property

[floede]

Prerequisites

• [ x ] I have added steps to test this contribution in the description below

Description

As discussed with Niels Lyngsø, this introduces a custom property to adjust the top property for #headerColumn, with the existing value as fallback.

In property-layout.element.ts I have added --umb-property-layout-header-top as the default to set the top value for #headerColumn.

[github-actions]

Hi there @floede, thank you for this contribution! 👍

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[floede]

@nielslyngsoe This is the small change we've discussed.

[Copilot]

Pull Request Overview

This PR introduces a custom CSS property --umb-property-layout-header-top to allow customization of the top positioning for the header column in property layouts. The change provides a way to override the default positioning while maintaining backward compatibility through CSS fallback values.

Key Changes:

• Added a custom CSS property for controlling header column positioning
• Maintained backward compatibility with existing default values
• Applied the custom property to both default and sticky positioning scenarios

[emmagarland]

Hi @floede

Thanks for your PR to fix an issue with the temp layout/custom property.

One of the Core Collaborators team is likely to review this as soon as possible - although as it sounds like you've already chatted to Niels about it too, which means HQ might review it first.

To avoid potential code duplication, if there is a related issue please can you add a comment relating to it?

Thanks again for your time and effort!

Best regards

Emma

[Matthew-Wise]

Sorry for the delay in merging this @floede thank you for your work!