I believe when you have Curtains on and if you use Windows 7style or Modern Style in Start11. The Startpanel will follow your Curtains graphics. If the graphics that set in Curtains has rounded corner in your start panel it will show up there. If it don't, you will see the rounded corner for a few moment when you apply the rounded corner in Start11 but it will revert back to what ever style that come with curtains.
Also note that Win10 and Win11 style does not be control by Curtains. That might be the reason why you see the bigger gaps on Win10 style not on Modern Style. Curtains just control Win 7 and Win 8/Modern style only.
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