Strange blue border in MapView of ArcGIS JS 4

Starting from ArcGIS JS 4.x, under some special conditions, the MapView will have a blue border when the MapView is focus, who genius get this geneless idea?

To get rid of this stupid box, style the following:

.esri-view-surface--inset-outline::after {   
    outline: none !important;
    padding: 0px !important;
}

So when this stupid design will come out? When ever your HTML got the following conditions, that stupid box will be shown when MapView is on focus:

body {
    margin: 0;
} 

#mapDiv {
    width: 100%
}

... The most weird API ever encountered