Remove the edges of an input in ionic 4

Ionic Framework
1

I am currently developing an app on ionic v4 and my problems is that I can not remove the edges of the focus, previously in ionic v3 only these lines of code are placed in variable.css and ready but in this version it does not work, thanks
With sass

  $text-input-md-highlight-color-invalid: transparent;
  $text-input-md-highlight-color-valid: transparent;
  $text-input-md-show-invalid-highlight: transparent;
  $text-input-md-highlight-color: transparent;
  $text-input-md-show-valid-highlight: transparent;
  $text-input-md-show-focus-highlight: transparent;
  $text-input-md-show-valid-highlight: $text-input-md-show-focus-highlight transparent;
  $text-input-md-show-invalid-highlight: $text-input-md-show-focus-highlight transparent;

bordes