Writer: Sidebar: Area: Unexpected jumping hover effect on button

[banobepascal]

Description

When hovering over the gradient color button, it shifts out of its original position, causing a layout shift. This unintended movement also affects surrounding elements, resulting in the overall layout becoming misaligned.

https://github.com/user-attachments/assets/3b040aa6-af99-4659-939e-3ad7c2a8df88

Steps to reproduce

1. Open a Writer document in Collabora Online.
2. Click on a Formula in the document
3. The Area dialog will open in the siderbar
4. On Fill, Select the dropdown and choose Gradient
5. Hover over the "First Gradient button"
6. And you will notice an unexpected jump of the element

Expected Behaviour:

Hovering over the button should only trigger visual changes (e.g., background color, shadow, etc.) without altering the button's position or affecting the layout of other elements.

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