How can I remove the white color of the background and apply a popup with transparent black

[nihp]

I have set a popup with a black transparent color. But I can't able to set the popup correctly, It have some space and a white background overlapped with the dropdown.

Like below image

Refer this SO too. Can you help me to resolve this.

https://stackoverflow.com/questions/65355791/how-to-fix-a-white-background-overlapped/65358073#65358073

[nihp]

@shehabic @shehabic-work Any update. How the white color will be change to transparent. I hae modified my layout, But unable to remove the white background.

Did you have any suggestion