custom-select shadow is not compatible with v4 shadows

Created by: omidgfx

as you can see, custom-select shadows on focus, is not compatible with v4 shadows. it's just like v3.x shadows when focusing on form-control s. even when both form-control and custom-select are using.

<select class="form-control custom-select">....</select>
<select class="custom-select">....</select>

You may try for yourself.