How do I apply a scale box scaling to non-full screen UMG widgets?

Hello! I just found out about what scale boxes do while trying different screen resolutions on my project and got to test and use them the way I intended but the inventory widget is causing me some trouble.

When a player clicks an inventory slot, a pop-up menu appears (image one), you can also drag items to another slot, which creates a new slot (image two) that follows the cursor until the item is dropped. The issue comes when the screen resolution is not 1920x1080: the entire widget is resized to fit the X but these widgets don’t get smaller like the rest, resulting in stuff like image four and six. How could I fix this?

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How it should look, drag slot as big as regular slots

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How it looks when resized

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How it should look, menu as tall as a slot when it shows two buttons

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How it looks resized