$my-icons-spacing: 10px; // give some space to avoid little pixel size issues on resize

@import "my-icons/*.png";

$my-icons-sprite-dimensions: true;

@include all-my-icons-sprites;

// the fun part

.small-icons { // overriding all sprites
  @include resize-sprite-set($my-icons-sprites, 40); // 40% sized
}

.some-part-of-my-site {
  @include resize-sprite-set($my-icons-sprites, 40, logo, ok); // will create overrides only for sprites "logo" and "ok"
}