Unable to use CSS extensions for styling same UI component type multiple ways

UI Builder
3

Hi @Owen_Fowler,

Please try this option:

 .levelSlider {
  .bl-slider-rail {
    opacity: 0;
  }

 .bl-slider-track {
    opacity: 0;
  }
 }

.bl-slider-rail and .bl-slider-track should be inside the class which you added. The second variant of adding the class was correct:
image

Regards,
Marina