npm i -D sass

$brand: #2563eb;
$bg: #0b1220;
$radius-md: 12px;

@mixin focusRing($color) {
  &:focus-visible {
    outline: 2px solid rgba($color, .45);
    outline-offset: 2px;
  }
}

.btn {
  background: $brand;
  border-radius: $radius-md;
  color: white;
  padding: .5rem 1rem;
  @include focusRing($brand);
}