ionic-framework/scss/ionic/_toggle.scss

// Toggle
// -------------------------------

/* the overall container of the toggle */
.toggle {
  display: inline-block;
}

/* hide the actual <input type="checkbox"> */
.toggle input[type="checkbox"] {
  display: none;
}

/* the background of the toggle's track area */
/* also the track appearance when the toggle is "off" */
.toggle .track {
  display: inline-block;
  box-sizing: border-box;
  width: $toggle-width;
  height: $toggle-height;
  border: solid $toggle-border-width $toggle-off-border-color;
  border-radius: $toggle-border-radius;
  background-color: $toggle-off-bg-color;
  cursor: pointer;

  transition-timing-function: ease-in-out;
  transition-duration: $toggle-transition-duration;
  transition-property: background-color, border;
}

/* the handle (circle) thats inside the toggle's track area */
/* also the appearance when the handle is "off" */
.toggle .handle {
  position: absolute;
  display: block;
  width: $toggle-handle-width;
  height: $toggle-handle-height;
  border-radius: $toggle-handle-radius;
  background-color: $toggle-handle-off-bg-color;
  transition: -webkit-transform $toggle-transition-duration ease-in-out;

  /* used to create a larger hit area to slide the handle */
  &:before {
    position: absolute;
    top: -2px;
    left: ( ($toggle-handle-width / 2) * -1) - 2;
    display: table;
    padding: ($toggle-handle-height / 2) + 3 ($toggle-handle-width + 2);
    content: " ";
  }
}


/* When the toggle is "on" */
.toggle :checked + .track {

  /* the track when the toggle is "on" */
  border-color: $toggle-on-border-color;
  background-color: $toggle-on-bg-color;

  /* the handle when the toggle is "on" */
  .handle {
    background-color: $toggle-handle-on-bg-color;
    -webkit-transform: translate3d( $toggle-width - $toggle-handle-width - ($toggle-border-width * 2) ,0,0);
  }
}