$opacities: (
  0  : 0,
  25 : 25,
  50 : 50,
  75 : 75,
  100: 100,
);

//  ==========================================================================
// OPACITY normal
//  ==========================================================================

  @each $size, $length in $opacities {
    .opacity-#{$size} { opacity: ($length*0.01) !important; }
  }

//  ==========================================================================
// OPACITY HOVER
//  ==========================================================================
  @each $size, $length in $opacities {
    .hvr-opacity-#{$size}.opacity:hover,
    .hvr-opacity-#{$size} .opacity:hover { opacity: ($length*0.01) !important; }
  }