Strange artifact on the numeric updown control and selection

[azerskyv]

Describe the question I'm using MatBlazor numeric updown control and selection control. When up/down arrow is clicked the green outline appears around the value. When selection is make in the drop down the green outline appears around selected item. It wouldn't go away until page is reloaded. Do you know what is it? What am I doing wrong and how to remove this outline?

Code:

@foreach (var option in @_rotationOptions) { @option }

(@_limitations.AccelerationMin - @_limitations.AccelerationMax) **Expected behavior** I don't expect that outline to appear, especially that I don't see it at your site and examples on-line. **Screenshots** Attaching... Thank you, Vlad. 

[PortalArm]

I had the same issue with MatTextField. I've found out default Blazor project template has some css related to valid/invalid class:

.valid.modified:not([type=checkbox]) {
    outline: 1px solid #26b050;
}
.invalid {
    outline: 1px solid red;
}

Commenting out these lines fixed the problem for me.