$bg-default-rgba: (
  10 : 10,
  25 : 25,
  50 : 50,
  75 : 75,
  85 : 85,
);

@each $size, $length in $bg-default-rgba {
  .bg-black-#{$size} { background-color: rgba(#000000, ($length*0.01)) !important;  }
}

@each $size, $length in $bg-default-rgba {
  .bg-white-#{$size} { background-color: rgba(#ffffff, ($length*0.01)) !important;  }
}